U.S. Ground Forces in the Indo-Pacific: Background and Issues for Congress

May 6, 2022 – August 30, 2022 R47096

U.S. Ground Forces in the Indo-Pacific:
August 30, 2022
Background and Issues for Congress
Andrew Feickert
Since the end of the Second World War in 1945, the U.S. military has maintained a significant
Specialist in Military
and enduring presence in the Indo-Pacific region. In the past, the United States’ strategic
Ground Forces
approach to the region has varied greatly. From September 11, 2001, until almost the next

decade, strategic emphasis was placed largely on global counterterrorism, primarily focused on
U.S. Central Command’s (USCENTCOM’s) and later U.S. Africa Command’s (USAFRICOM’s)

areas of operation. Starting around 2004, the George W. Bush Administration began to consider
strengthening relations with allies in Asia and potentially revising U.S. doctrine and force posture in the region to improve
U.S. capabilities.
In 2011, the Obama Administration announced the United States would expand and strengthen its existing role in the Asia-
Pacific region. Referred to as the “Rebalance to Asia,” this strategic shift away from counterterrorism was intended to devote
more effort to influencing the development of the Asia-Pacific’s norms and rules, particularly as China was emerging as an
ever-more influential regional power.
While many view the Indo-Pacific as primarily a Navy- and Air Force-centric region, the Army and Marine Corps have a
long and consequential presence in the region and are modifying their operational concepts, force structure, and weapon
systems to address regional threats posed primarily by North Korea and China. The Army and Marines each play a critical
role in the region, not only in the event of conflict but also in deterrence, security force assistance, and humanitarian
assistance operations.
Congress continues to play an active and essential role in Indo-Pacific security matters. The Pacific Deterrence Initiative
(PDI), created by the FY2021 National Defense Authorization Act (NDAA; P.L. 116-283, §1251) is just one example of
congressional involvement in regional security efforts. The February 2022 Russian invasion of Ukraine and its present and
future implications for European and Indo-Pacific security will likely increase both congressional interest and action in the
near term and for the foreseeable future.
Potential issues for Congress include
 the role of U.S. ground forces in the Indo-Pacific region,
 the posture of U.S. ground forces in the Indo-Pacific region,
 U.S. ground forces execution of regional wartime missions, and
 the potential impact of the Ukrainian conflict on U.S. ground forces in the Indo-Pacific region.

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U.S. Ground Forces in the Indo-Pacific: Background and Issues for Congress

Why Is this Issue Important to Congress?
In 2011, the Obama Administration announced the United States would expand and strengthen its
existing role in the Asia-Pacific region.1 Referred to as the “Rebalance to Asia,” this strategic
shift away from the post 9-11 strategic emphasis on counterterrorism signaled an intention to
“devote more effort to influencing the development of the Asia-Pacific’s norms and rules,
particularly as China emerges as an ever-more influential regional power.”2 Some observers
suggested that “for the last decade, the Pentagon has been promising a more distributed and
resilient posture in the Indo-Pacific, but has not kept that promise. Highly-concentrated with few
active or passive defenses, American forces—and lives—remain dangerously vulnerable to
attack.”3 The Department of Defense (DOD) has been described as being “locked in a tense
debate over whether to base American troops and high-end weapons within the reach of newly-
capable Chinese missiles.”4
Congress has debated this issue. Some contend that past and current Administrations have not
done enough, suggesting that DOD’s rhetoric in this regard does not match its actions or budget
requests, and suggest some are “struggling to understand the disconnect.”5 In the past, others have
said plans to implement U.S. Indo-Pacific military strategy were “overly ambitious” and that
“we’re constantly chasing our tail, unable to do what [the National Defense Strategy] say’s we’re
supposed to be able to do. That needs to get more realistic.”6
Congress, in its oversight, authorization, and appropriations roles, may continue to play an active
and important part in in the ongoing policy debate about U.S. Indo-Pacific military strategy and
the role that U.S. ground forces are expected to play in the region, especially in force structure
and in capabilities for those forces.
A Brief History of U.S. Military Forces in the
Pacific Region7
Since the end of the Second World War in 1945, the U.S. military has maintained a significant
and enduring presence in the Indo-Pacific region. Earlier, the first U.S. presence in Asia was
constituted by merchant ships trading with China in 1784. After the War of 1812, the United
States realized it needed to protect its interests in the region. In 1821, the Navy created the Pacific
Squadron, and in 1835, it created the East India Squadron, with both squadrons having embarked
Marine detachments, as was the practice at the time. The first U.S. military operations in the
region were two punitive expeditions against Sumatran pirates in 1832 and 1839. In 1844, as a
result of a treaty with China, U.S. missionaries began educational and ministerial work in China’s

1 For detailed information on the Pacific Pivot, see CRS Report R42448, Pivot to the Pacific? The Obama
Administration’s “Rebalancing” Toward Asia, coordinated by Mark E. Manyin.
2 Ibid., p. 1.
3 Dustin Walker, “The Pentagon is in Desperate Need of an Intervention from the Top,” War on the Rocks, January 27,
2022.
4 Jack Detsch, “The Pentagon Faces Tense Fight Over Pacific Pivot,” Foreign Affairs, June 7, 2021.
5 Ibid.
6 Ibid.
7 Information from this section is taken from United States Army Pacific (USARPAC), “America’s Theater Army for
the Indo-Pacific,” September 2021, and Christopher L. Kolakowski, “A Short History of U.S. Involvement in the Indo-
Pacific,” Journal of Indo Pacific Affairs, 2018, pp. 14-20.
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interior communities. In 1853, Commodore William Perry took the East India Squadron to Tokyo
Bay, opening Japan to the western world.
At the end of the 19th century, U.S. military presence in the Indo-Pacific increased. The 1867
purchase of Alaska and the 1898 annexation of Hawaii extended U.S. territory, presence, and
influence in the region. The Spanish-American War of 1898 is credited with establishing the
United States as a prominent Pacific power as a result of U.S. military victories in Manila Bay
and the subsequent capture of Manila and Guam in 1898. After Spain ceded its colony of the
Philippines to the United States, another three years of war ensued between the United States and
pro-independence Filipinos. After these victories, forward U.S. military ground presence was an
important means to secure these new territories.
In 1900, in response to the Boxer Rebellion in China, the U.S. Army and Marines were sent to
participate in the international China Relief Expedition (which included forces from Great
Britain, Germany, Russia, France, Japan, Italy, and Austria) to rescue United States citizens,
European nationals, and other foreign nationals threatened by the rebellion. In the aftermath of
the Boxer Rebellion, the United States permanently stationed the 4th Marine and 15th Army
Infantry Regiments in China to protect American interests. To support further operations on the
Asian continent, the U.S. Army also established forward operating bases in Japan.
In 1907, the U.S. Army and Navy decided to make Pearl Harbor, in the then territory of Hawaii,
the principal U.S. naval base in the Pacific, strengthening Army presence in the region and
leading to the establishment of Ft. Shafter on the island of Oahu. During the era leading up to and
after the First World War, in response to crises in the Pacific-Philippines (1905-1916) and Russian
Siberia (1918-1920), the U.S. government deemed the use of Indo-Pacific based ground forces
necessary to provide stability and protect U.S. citizens and interests.
After the Second World War, in which the Indo-Pacific region was a major theater of operations,
the United States permanently established s large-scale ground force presence in the region to
face the challenges of the Cold War. Although Europe remained relatively peaceful after 1945,
U.S. troops fought wars in Korea (1950-1953) and Vietnam (1955-1975). While U.S. ground
force levels in the region have diminished since the Vietnam War, the U.S. Army still maintains
approximately 93,000 troops in and around the region, and the Marines maintain about 86,000
Marines both ashore and afloat.8
U.S. National Security and the Indo-Pacific Region
U.S. Indo-Pacific Command (USINDOPACOM) is the U.S. military’s Geographic Combatant
Command responsible for “using and integrating United States Army, Navy, Air Force and
Marine Corps forces within the USINDOPACOM area of responsibility (AOR) to achieve U.S.
national security objectives while protecting national interests.”9 The INDOPACOM AOR is
depicted in Figure 1.

8 USINDOPACOM, at https://www.pacom.mil/About-USINDOPACOM/, accessed February 2, 2022.
9 USINSOPACOM, at https://www.pacom.mil/About-USINDOPACOM/USPACOM-Area-of-Responsibility/,
accessed February 7, 2022.
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Figure 1. USINDOPACOM Area of Responsibility

Source: https://www.pacom.mil/About-USINDOPACOM/USPACOM-Area-of-Responsibility/, accessed February
7, 2022.
Strategic Approach
In the past, the United States’ strategic approach to the region has varied greatly. From September
11, 2001, until almost the next decade, strategic emphasis was placed on global counterterrorism,
primarily focused on U.S. Central Command’s (USCENTCOM’s) and later U.S. Africa
Command’s (USAFRICOM’s) areas of operation. However, starting as early as 2004, the George
W. Bush Administration began to consider strengthening relations with allies in Asia, revising
U.S. force posture in the region, and examining doctrinal innovations to enhance U.S. military
capabilities in Asia.10

10 Nina Silove, “The Pivot Before the Pivot: U.S. Strategy to Preserve the Power Balance in Asia,” International
Security, vol. 40, no. 4 (Spring 2016), p. 67, and CRS Report R42448, Pivot to the Pacific? The Obama
Administration’s “Rebalancing” Toward Asia, coordinated by Mark E. Manyin, p. 2.
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U.S. Ground Forces in the Indo-Pacific: Background and Issues for Congress

In 2011, the Obama Administration announced that the United States would expand and
strengthen its existing role in the Asia-Pacific region.11 Referred to as the “Rebalance to Asia,”
this strategic shift away from counterterrorism was intended to “devote more effort to influencing
the development of the Asia-Pacific’s norms and rules, particularly as China emerges as an ever-
more influential regional power.”12 Militarily, the Obama Administration
 announced new troop deployments to Australia and naval deployments to
Singapore, as well as new areas for military cooperation with the Philippines, and
 stated that, notwithstanding reductions in overall defense spending, U.S. military
presence in East Asia would be strengthened, more distributed, flexible, and
politically sustainable.13
The Obama Administration’s 2015 National Security Strategy committed to continuing the
rebalancing to Asia and the Pacific and noted “the potential of our relationship with India.”14
Continuing the emphasis on the Indo-Pacific region, the Trump Administration’s 2017 National
Security Strategy noted
China presents its ambitions as mutually beneficial, but Chinese dominance risks
diminishing the sovereignty of many states in the Indo-Pacific. States throughout the region
are calling for sustained U.S. leadership in a collective response that upholds a regional
order respectful of sovereignty and independence.15
Militarily, the Trump Administration sought to “maintain U.S. strategic primacy in the Indo-
Pacific region” and to “ensure North Korea does not threaten the United States and its allies.”16
DOD’s 2019 Indo-Pacific Strategy Report, which designated the Indo-Pacific as DOD’s priority
theater, outlined three components through which these security objectives were to be achieved:17
 Preparedness. Peace through strength by employing effective Joint Force
deterrence, which, if required, would be prepared to win any conflict from its
onset. DOD, alongside allies and partners, would ensure that combat-credible
forces were forward-postured in the region. Furthermore, DOD would prioritize
investments that ensured lethality against high-end adversaries.
 Partnerships. DOD would reinforce its commitment to established alliances and
partnerships and expand and deepen relationships with new partners.
 Promotion of a Networked Region. DOD would strengthen and evolve U.S.
alliances and partnerships into a networked security architecture. DOD would
also continue to cultivate intra-Asian security relationships to deter aggression,
maintain stability, and ensure free access to common domain.18

11 CRS Report R42448, Pivot to the Pacific? The Obama Administration’s “Rebalancing” Toward Asia, coordinated
by Mark E. Manyin, p. 1.
12 Ibid.
13 Ibid.
14 National Security Strategy of the United States of America, February 2015, Introduction.
15 National Security Strategy of the United States, February 2017, p. 46.
16 U.S. Strategic Framework for the Indo-Pacific, at https://trumpwhitehouse.archives.gov/wp-content/uploads/2021/01/
IPS-Final-Declass.pdf, accessed February 7, 2022, p. 1.
17 The Department of Defense, “Indo-Pacific Strategy Report: Preparedness, Partnerships, and Promoting a Networked
Region,” June 1, 2019, Message from the Secretary of Defense.
18 Ibid., Message from the Secretary of Defense.
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President Biden’s March 2021 Interim National Security Strategic Guidance continued to focus
on “allow(ing) us to prevail in strategic competition with China or any other nation,” noting that
the “growing assertiveness of China and Russia” poses a significant concern to the security of
democratic nations.19
On February 11, 2022, the Biden Administration released its Indo-Pacific Strategy.20 Militarily,
the new strategy states that
[w]e will renew our focus on innovation to ensure the U.S. military can operate in rapidly
evolving threat environments, including space, cyberspace, and critical- and emerging-
technology areas. We are developing new concepts of operations, building more resilient
command and control, increasing the scope and complexity of our joint exercises and
operations, and pursuing diverse force-posture opportunities that will strengthen our ability
to operate forward and more flexibly with allies and partners.21
While the Administration’s 2022 strategy provides little detail on the role that U.S. ground forces
will play, future associated strategic documents from DOD and USINDOPACOM might provide
specific details on the role of the Army and Marines in the Indo-Pacific.
Although growing strategic emphasis on the Indo-Pacific region has been a central feature in U.S.
policy since around 2004, some experts question the efficacy of the “Rebalance to Asia.” One
analyst suggests
Confronting the strategic threats that China poses to the United States is a daunting task
even if the United States is able to focus the appropriate strategic resources and attention.
However, perhaps it was never truly possible for the world’s greatest superpower, with
binding strategic alliances spanning the globe, to be able to have a laser-like focus on one
region of the world. In that case, a true “pivot” to Asia was never really possible. The
United States, whether it likes it or not, is still viewed as the world’s policeman and will
naturally be brought into global affairs in a way that China will not.22
Another analyst questions U.S. strategic efforts focused on the Indian Ocean region
But the United States’ thin military presence in the Indian Ocean region is not a gap that
needs filling. It is proportional to U.S. interests in the region compared with those in other
parts of Asia. Expanding the navy’s presence in the Indian Ocean could make sense if the
United States needed to be prepared for the sudden outbreak of war there. But China’s main
conflict is on land in the Himalayas—against India, a dispute that does not concern U.S.
interests. And China will not remain passive as it perceives the U.S. military further
encircling it. The surest path to preventing war in the Indian Ocean is restraint, not more
troops in defense of a nonexistent redline.23
In this regard, there will likely continue to be questions about the U.S. strategic approach in the
Indo-Pacific region.

19 2021 Interim National Security Strategic Guidance, March 2021, p. 20.
20 Indo-Pacific Strategy of the United States, February 2022, https://www.whitehouse.gov/wp-content/uploads/2022/02/
U.S.-Indo-Pacific-Strategy.pdf.
21 Ibid., p. 12.
22 Peter Birgbauer, “The US Pivot to Asia Was Dead on Arrival,” The Diplomat, March 31, 2022.
23 Van Jackson, “America’s Indo-Pacific Folly,” Foreign Affairs, March 12, 2021.
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Greater Emphasis on the Navy and Air Force in
Indo-Pacific Strategy
For military planning, the Indo-Pacific Theater has been characterized and defined by geography,
particularly its size and distance. USINDOPACOM notes the AOR “encompasses about half the
earth’s surface, stretching from the waters off the west coast of the U.S. to the western border of
India, and from Antarctica to the North Pole.”24 By percentage, in 2015, the INDOPACOM AOR
was composed of 83% water and 17% land.25 The combatant command grew in 2018 when India
was added to U.S. Pacific Command’s (USPACOM’S) area of responsibility, resulting in
USPACOM being renamed USINDOPACOM. The size and maritime geography of the Indo-
Pacific AOR has historically impacted the type of U.S. military forces and capabilities in the
region.
In the 1990s, after witnessing two demonstrations of U.S. military power—the Gulf War and the
third Taiwan Strait Crisis—People’s Republic of China (PRC) leadership realized that it “lacked
the technology to wage a modern war and to prevent foreign powers from intervening in the
region” and accelerated modernization efforts begun in the late 1970s to catch up to top-tier
militaries.26 PRC naval modernization was a central aspect in improving its military. China
expanded fleet numbers and capabilities over the decades, and growing Chinese naval power was
viewed with heightened concern by the United States and regional allies.27
In recognition of increasing Chinese power and ambitions in the region, U.S. policymakers began
to reconsider strategic priorities and force posture, and to undertake efforts to shift emphasis to
the Indo-Pacific region. In 2012, reflecting the strategic rebalance to the Pacific, the Obama
Administration published “Sustaining U.S. Leadership: Priorities for 21st Century Leadership.”28
This strategic review stated that the U.S. military would no longer size its forces to fight in two
nearly simultaneously major theater wars. The easing of this requirement resulted in substantial
cuts to ground forces—about 80,000 active duty Army soldiers and about 22,000 Marines. The
strategy proposed only minor cuts to naval force structure.
In 2013, DOD published the “Air-Sea Battle Concept,” which stated that “instead of focusing on
the land domain from the air, the Concept describes integrated operations across all five domains
(air, land, sea, space, and cyberspace) to create advantage.”29 While the Air-Sea Battle Concept
did not exclude land forces, some critics noted “the missing part of the Air Sea Battle concept was
the land portion, basically how the land forces could be used to allow U.S. forces to gain access
to a contested area.”30 In 2015, the Air-Sea Battle Concept was changed to “Joint Concept for

24 USINDOPACOM, at https://www.pacom.mil/About-USINDOPACOM/, accessed February 11, 2022.
25 Admiral Samuel J. Locklear, III, Commander, US Pacific Command, “PACOM Before the House Appropriations
Committee Remarks,” March 18, 2015.
26 Lindsay Maizland, “China’s Modernizing Military,” Council on Foreign Relations, February 5, 2020.
27 For additional information on Chinese naval modernization, see CRS Report RL33153, China Naval Modernization:
Implications for U.S. Navy Capabilities—Background and Issues for Congress, by Ronald O'Rourke.
28 Information in this section is taken from Department of Defense, “Sustaining U.S. Leadership: Priorities for 21st
Century Leadership,” January 2012, and CRS Report R42448, Pivot to the Pacific? The Obama Administration’s
“Rebalancing” Toward Asia, coordinated by Mark E. Manyin.
29 DOD Air-Sea Battle Office, “Air- Sea Battle Service Collaboration to Address Anti-Access & Area Denial
Challenges,” May 2013, p. i.
30 Sam LaGrone, “Pentagon Drops Air Sea Battle Name, Concept Lives On,” U.S. Naval Institute News, January 20,
2015.
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Access and Maneuver in the Global Commons (JAM-GC),” which “include[d] a focus on
including U.S. land forces into the wider concept.”31
The geography of the Indo-Pacific, Chinese naval modernization, cuts to land forces, and the
emergence of a naval- and air-centric concept of operations could have suggested to some that the
Navy and Air Force would have leading roles in the Indo-Pacific Theater. This view was likely
reinforced further by range limitations of land-based Army and Marine weapon systems and their
perceived utility against Chinese naval and air threats. Some experts have questioned the role and
need for the Army in the Indo-Pacific region, with one piece noting
A large active-duty Army is not needed to protect the United States. America’s security
interests are far better served through deterrence and the projection of power by sea and
air. Given the geography of the Indo-Pacific and the reality of future spending constraints,
ensuring U.S. naval supremacy over China will require prudent increases to the Navy’s
budget at the expense of the Army.32
Service chiefs have called for a larger budget in light of the strategic prioritization of the Indo-
Pacific region, particularly regarding China as a “pacing threat.” Chief of Naval Operations
(CNO) Admiral Mike Gilday reportedly stated in January 2020
We need more money. If you believe that we require overmatch in the maritime, if you
believe that we’re going to execute distributed maritime operations and operate forward in
greater numbers now, that we need more iron, then we need more topline. Budgeting as
usual, which means a one-third, one-third, one-third cut, does not reflect the strategy. It
isn’t necessarily aligned with where we need to go against the pacing threat that we face.33
Reportedly, the CNO had made these arguments to defense leadership before, but this was the
first time the CNO had “publicly made the case for his service to grow at a faster rate than the
other services.”34
U.S. Indo-Pacific Headquarters and Ground Forces
Of critical importance to any discussion about the role and need for U.S. ground forces in the
Indo-Pacific region is where they are based. Figure 2 provides an overview of major
headquarters and U.S. Army and Marine Corps forces based in the Indo-Pacific, as well as units
based in the United States dedicated to supporting operations in the region. In the event of crisis,
other units may be allocated to the Indo-Pacific region. These units are not depicted in Figure 2.

31 Ibid.
32 Gil Barndollar and Sascha Glaeser, “The United States Must Put the Navy First,” Defense News, January 31, 2022.
33 Paul McCleary, “Navy CNO Fires First Budget Salvo: We Need More Money Than Army, Air Force,” Breaking
Defense, January 14, 2020.
34 Ibid.
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Figure 2. Major U.S. Headquarters and Army and Marine Units in and Around the
Indo-Pacific Region

Sources: Graphic produced by CRS Graphics. Information is taken from United States Army Pacific
(USARPAC), “America’s Theater Army for the Indo-Pacific,” September 2021, and information provided to the
author by the Marine Corps Legislative Liaison Office.
Note: Numbers of personnel associated with locations and units are approximate and includes additional units
not depicted in Figure 2.
Headquarters and Major Ground Units in the
Indo-Pacific
A variety of ground units are stationed in and around the Indo-Pacific region, and a number of
headquarters provide command and control for these forces. The following sections provide
information on the major headquarters and active duty units identified in Figure 2.35
Hawaii
United States India-Pacific Command (USINDOPACOM). One of six geographic combatant
commands designated by DOD’s Unified Command Plan (UCP), USINDOPACOM is in charge
of employing and integrating U.S. Army, Navy, Air Force, and Marine Corps forces allocated to
the USINDOPACOM AOR to achieve U.S. national security objectives. It does so by promoting
stability in the region through security cooperation, encouraging peaceful development,

35 For additional information on types of Army and Marine Corps Units, see CRS In Focus IF10571, Defense Primer:
Organization of U.S. Ground Forces, by Barbara Salazar Torreon and Andrew Feickert.
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responding to contingencies, deterring aggression, and, when necessary, conducting combat
operations.36 USINDOPACOM is located at Camp H.M. Smith on the island of Oahu.
U.S. Army Pacific (USARPAC). USARPAC is the Army Service Component Command
(ASCC) for INDOPACOM. It provides continuous oversight and control of Army operations
throughout the INDOPACOM AOR with the exception of the Korean Peninsula.37 USARPAC is
located at Fort Shafter on the island of Oahu.
USARPAC Theater Enabling Commands. USARPAC has a number of theater-enabling
commands that support operations in the Indo-Pacific AOR, including an engineer brigade, a
military police brigade, a military intelligence brigade, and an air and missile defense brigade.
25th Infantry Division. The 25th Infantry Division, located at Schofield Barracks, Oahu,
commands multiple brigades and is a primary tactical headquarters for combat operations. These
infantry division units participate in several yearly exercises and operations in support of
USARPAC and the Indo-Pacific region. Some of the 25th Infantry Division’s major units include
 two infantry brigade combat teams (IBCTs),
 one combat aviation brigade (CAB), and
 one artillery brigade.

U.S. Marine Corps Forces, Pacific (MARFORPAC).38 MARFORPAC is the Marine Corps
Service Component Command for USINDOPACOM. MARFORPAC is the largest Marine Corps
field command and constitutes two-thirds of the Marine Corps’ operating forces. MARFORPAC
commands all Marine Corps forces assigned to USINDOPACOM. The MARFORPAC
Commander also serves as Commanding General, Fleet Marine Forces, Pacific.39 MARFORPAC
headquarters is located at Camp H.M. Smith on Oahu.
3rd Marine Littoral Regiment (MLR).40 On March 4, 2022, the 3rd Marine Regiment, part of the
Okinawa-based 3rd Marine Expeditionary Force (MEF), was redesignated as the 3rd Marine
Littoral Regiment (MLR) and stationed at Kaneohe Bay, HI.41 MLRs are being designed by the
Marine Corps to deploy more quickly than traditional Marine units and to operate inside enemy
weapon engagement zones and to be more logistically self-sufficient than existing Marine
infantry regiments.42
Alaska
11th Airborne Division.43 On June 6, 2022, U.S. Army Alaska, headquartered at Joint Base
Elmendorf-Richardson and Fort Wainwright, was redesignated as the 11th Airborne Division. The

36 USINDOPACOM, at https://www.pacom.mil/About-USINDOPACOM/USPACOM-Area-of-Responsibility/,
accessed February 24, 2022.
37 USARPAC, at https://www.army.mil/organization/, accessed February 24, 2022.
38 MARFORPAC, at https://www.marforpac.marines.mil/Unit-Home/About/, accessed February 25, 2022.
39 MARFORPAC, at https://www.marforpac.marines.mil/Unit-Home/About/, accessed February 24, 2022.
40 For additional information on Marine Littoral Regiments (MLRs), see CRS In Focus IF12200, The U.S. Marine
Corps Marine Littoral Regiment (MLR), by Andrew Feickert.
41 USINDOPACOM, at https://www.pacom.mil/Media/News/News-Article-View/Article/2955826/redesignated-3rd-
marine-regiment-becomes-3rd-marine-littoral-regiment/, accessed August 29, 2022.
42 Aidan Quigley, “Marine Corps to Formally Stand Up First Marine Littoral Regiment this Week,” InsideDefense.com,
February 28, 2022.
43Joe Lacdan, “Army re-activates historic airborne unit, reaffirms commitment to Arctic Strategy,” U.S. Army News,
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11th Airborne Division is to be a major subordinate command of USARPAC. The 11th Airborne
Division is to support operations worldwide, theater engagement in the Pacific/Arctic, and
military operations in the Alaskan area of operations. As part of this redesignation, the Army also
redesignated the 1st Stryker Brigade Combat Team from the Hawaii-based 25th Infantry Division
(stationed at Ft. Wainwright) and the 4th Infantry Brigade Combat Team—also from the 25th
Infantry Division (stationed at Joint Base Elmendorf-Richardson)—into the 1st and 2nd Infantry
Brigade Combat Teams of the 11th Airborne Division, respectively. In addition, a CAB is also
stationed at Joint Base Elmendorf-Richardson.44 Army leadership stated that the 11th Airborne
Division was to be equipped with cold weather gear over the next one to two years and would
serve as the Army’s leading experts for arctic military operations.45
Washington State
U.S. Army I Corps. First Corps (or I Corps) is a headquarters commanded by a Lieutenant
General (three stars), that manages daily activities for more than 44,000 soldiers stationed at Joint
Base Lewis-McChord (JBLM) and across the Pacific, including Hawaii and Alaska. I Corps’
major subordinate commands include 7th Infantry Division, 25th Infantry Division (Schofield
Barracks, HI), and U.S. Army Alaska.46 Some of I Corps’ corps-level assigned forces include
 an artillery brigade,
 a military intelligence brigade,
 an engineer brigade, and
 a military police brigade.
7th Infantry Division.47 The 7th Infantry Division, stationed at JBLM, commands multiple
brigades and is a primary tactical headquarters for combat operations. Seventh Infantry Division
units participate in several yearly exercises and operations in support of U.S. Army Pacific and
the Indo-Pacific region. Some of the 7th Infantry Division’s major units include
 two active duty SBCTs,
 an affiliated Army National Guard (ARNG) SBCT, and
 a CAB.
1st Multi-Domain Task Force (MDTF).48 The 1st MDTF, stationed at JBLM, is a brigade-sized,
theater-level organization designed to synchronize precision effects and fire in all domains (air,
land, sea, space, and cyber) against adversary anti-access/area denial (A2/AD) networks so that
joint forces can execute their operational plan (OPLAN)-directed missions in the Indo-Pacific
region.

June 8, 2022.
44 JBLM, at https://www.jber.jb.mil/Units/Army/, accessed February 25, 2022.
45Joe Lacdan, “Army re-activates historic airborne unit, reaffirms commitment to Arctic Strategy,” U.S. Army News,
June 8, 2022.
46 I Corps, at https://www.army.mil/icorps#org-about, accessed February 24, 2022.
47 7th ID, at https://www.army.mil/7thid#org-about, accessed February 24, 2022.
48 For additional information on Multi-Domain Tasks Forces (MDTF), see CRS In Focus IF11797, The Army’s Multi-
Domain Task Force (MDTF), by Andrew Feickert.
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5th Security Force Assistance Brigade (SFAB).49 SFABs are specialized units with the primary
mission of conducting training, advising, assisting, enabling, and accompanying operations with
allied and partner nations.50 The 5th SFAB, stationed at JBLM, works for the Commander of
USINDOPACOM and supports theater security cooperation efforts by training with partner nation
security forces in the region.
California
1st Marine Expeditionary Force (MEF).51 A subordinate unit of MARFORPAC, 1st MEF is
stationed at Camp Pendleton, California. Its mission is to provide a globally responsive,
expeditionary Marine Air-Ground Task Force (MAGTF) capable of providing forces for crisis
response, forward presence, and major combat operations. Major 1st MEF units include
 1st Marine Division,
 1st Marine Logistics Group,
 3rd Marine Aircraft Wing,
 11th Marine Expeditionary Unit (MEU),
 13th MEU, and
 15th MEU.
Republic of Korea (ROK)52
United States Forces Korea (USFK). USFK is a sub-unified command of USINDOPACOM.
The USFK commander’s responsibilities are to “administer the U.S.-Republic of Korea Defense
Treaty; to conduct reception, staging, onward movement, and integration of U.S. forces (as
necessary during Armistice and war); to conduct Non-Combatant Evacuation Operations (NEO)
if necessary; and to coordinate all U.S. military support to the Republic of Korea.”53 Commander
USFK is also the commander of United Nations Command (UNC) and Combined Forces
Command (CFC), which “are distinct organizations with different missions, reporting chains, and
authorities.”54 USFK headquarters is located at Camp Humphreys, ROK.
8th Army. The 8th Army is the Army’s only field army. Commanded by a Lieutenant General
(three star), it conducts operational tasks on the Korean Peninsula and serves as the Army’s
component command to USFK. The 8th Army has the ability to command and control multiple
corps-level units during combat operations. Major army-level 8th Army units include an air and

49 For additional information on Security Force Assistance Brigades (SFABs), see CRS In Focus IF10675, Army
Security Force Assistance Brigades (SFABs), by Andrew Feickert.
50 U.S. Army, at https://www.goarmy.com/careers-and-jobs/current-and-prior-service/advance-your-career/security-
force-assistance-brigade.html, accessed February 24, 2024.
51 1st MEF, at https://www.imef.marines.mil/, accessed February 25, 2022.
52 For additional information on the Republic of Korea, see CRS In Focus IF10165, South Korea: Background and U.S.
Relations, by Mark E. Manyin, Emma Chanlett-Avery, and Brock R. Williams, and CRS In Focus IF11388, U.S.-South
Korea Alliance: Issues for Congress, by Emma Chanlett-Avery and Caitlin Campbell.
53 Senate Armed Service Committee, “Advance Policy Questions for General Paul LaCamera, USA, Nominee to be
Commander, United Nations Command, Commander, Republic of Korea-United States Combined Forces Command,
and Commander, United States Forces Korea,” May 14, 2021, p. 1.
54 Ibid.
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missile defense brigade, a military intelligence brigade, and a signals brigade.55 The 8th Army
headquarters is located at Camp Humphreys, ROK.
2nd Infantry Division. The 2nd Infantry Division/ROK-U.S. Combined Division is the last
remaining permanently forward-stationed division in the U.S. Army. The 2nd Infantry Division
deters aggression and maintains peace on the Korean Peninsula.56 Second Infantry Division
headquarters is located at Camp Humphreys, ROK. Major units include
 a rotational armored brigade combat team (ABCT) from other Army divisions
stationed in the United States,
 two field artillery brigades, and
 a CAB.57
U.S. Marine Corps Forces Korea (MARFORK). MARFORK is the Marine Corps’ service
component for USFK and the UNC. It commands all U.S. Marine forces assigned to USFK and
UNC and advises USFK and UNC on the capabilities, support, and proper employment of Marine
forces for the defense of the ROK.58 MARFORK headquarters is located at Camp Humphreys,
ROK.
Japan59
U.S. Forces Japan. United States Forces, Japan (USFJ) conducts operations, activities, and
actions in Japan to support USINDOPACOM. USFJ manages the U.S.–Japan Alliance and is
responsible for planning, coordinating, and supporting U.S. defense issues in Japan.60
U.S. Army Japan. U.S. Army Japan facilitates multilateral cooperation with regional partners
and allies through engagements, training, and exercises. It also partners with the Japanese Ground
Self Defense Force to enhance interoperability, capability, and capacity.61 Major units include
 an air defense brigade,
 an aviation battalion, and
 a military intelligence brigade.
Marine Forces Japan. Marine Forces Japan primarily consists of two F-35B squadrons stationed
at Marine Corps Air Station Iwakuni, Japan.
Okinawa (Japan)
3rd Marine Expeditionary Force (MEF). The 3rd MEF, commanded by Lieutenant Generals
(three stars), is currently headquartered in Okinawa, Japan, and is responsible for maintaining a
forward presence in support of the Treaty of Mutual Cooperation and Security between the United

55 United States Army Pacific, “America’s Theater Army for the Pacific,” September 2021, pp. 12-13.
56 Taken from 2nd Infantry Division at https://www.2id.korea.army.mil/, accessed February 28, 2022.
57 United States Army Pacific, “America’s Theater Army for the Pacific,” September 2021, p. 13.
58 Taken from U.S. Marine Forces Korea at https://www.marfork.marines.mil/, accessed February 28, 2022.
59 For additional information on Japan, see CRS In Focus IF10199, U.S.-Japan Relations, coordinated by Emma
Chanlett-Avery.
60 U.S. Forces Japan, at https://www.usfj.mil/About-USFJ/, accessed March 8, 2022.
61 U.S. Army Japan, at https://www.usarj.army.mil/about/mission/, accessed March 8, 2022.
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States and Japan, and other regional allies. The 3rd MEF also conducts combined operations and
training in the region in support of Theater Security Cooperation efforts.62 Major units include
 3rd Marine Division,
 1st Marine Aircraft Wing,
 3rd Marine Logistics Group,
 3rd Marine Expeditionary Brigade (MEB),
 31st MEU, and
 3rd Marine Expeditionary Force Information Group.63
Relocation of 3rd MEF Forces from Okinawa
Based on an agreement with the Japanese government, the 3rd MEF is planning to relocate
selected forces from Okinawa to Guam, Hawaii, and elsewhere.64 It was reported that the transfer
from Okinawa to Guam could begin as early as October 2024 and take 18 months to complete.65
This realignment calls for 4,100 Okinawa-based Marines to be relocated to Guam, along with 900
Marines from elsewhere. In addition, approximately 2,700 more Okinawa-based Marines would
be sent to Hawaii and 800 would go to the continental United States, with another 1,300 Guam-
based Marines composing most of the 2,500-person Marine Rotational Force in Darwin,
Australia. Plans to shift the Futenma Marine Air Base within Okinawa from a densely populated
city to a less crowded coastal area, which was agreed upon by Japan and the United States in the
1990s, is meeting resistance from some native Okinawans.66 It is not known how many Marines
will be left on Okinawa once the realignment is completed.
Guam67
U.S. Army forces on Guam consist primarily of about 2,000 National Guard soldiers and
approximately 100 Active soldiers manning a Terminal High Altitude Area Defense (THAAD)
battery. As previously noted, the Marines plan to relocate approximately 5,000 Marines to Guam
beginning in Fall 2024.
Australia
Marine Rotational Force–Darwin. On November 16, 2011, Australian Prime Minister Gillard
and President Obama announced an extension of Australia’s existing defence alliance with the

62 3rd MEF, at https://www.iiimef.marines.mil/.
63 Ibid.
64 For additional information, see CRS In Focus IF10672, U.S. Military Presence on Okinawa and Realignment to
Guam, by Emma Chanlett-Avery, Christopher T. Mann, and Joshua A. Williams.
65 Information in this section is taken from Matthew M. Burk, “Marines’ Move from Okinawa to Guam Could Begin as
Early as October 2024, Report Says,” Stars and Stripes, May 16, 2019.
66 Sheryl Lee Tian Tong, “Our Land, Our Life: Okinawans Hold Out Against New U.S. Base in Coastal Zone,”
Mongabay, November 25, 2021.
67Information in this section is taken from Matthew M. Burk, “Marines’ Move from Okinawa to Guam Could Begin as
Early as October 2024, Report Says,” Stars and Stripes, May 16, 2019.
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United States. Called the United States Force Posture Initiatives (USFPI), the extension included
the establishment of the Marine Rotational Force–Darwin (MRF-D).68
The Australian Department of Defense noted
The Marine Rotational Force-Darwin (MRF-D) sees a contingent of U.S. Marines and their
equipment rotate through Northern Australia during the dry season. While in Australia, the
MRF-D undertake a range of activities, combined exercises and training with the
Australian Defence Force (ADF) and regional partners. The MRF-D has grown in size and
complexity since the first rotation of 200 US Marines through Darwin in 2012, through to
reaching the milestone of 2500 Marines in 2019. It is now a highly capable force that
provides significant opportunities to enhance interoperability with the Australian Defence
Force. MRF-D composition will vary from year to year as a consequence of the activities
being undertaken with the ADF and regional partners each year.69
The Role of U.S. Ground Forces in the
Indo-Pacific Region
Essentially, the Army and Marines have four basic roles in the Indo-Pacific region (summarized
below): combat operations, deterrence, security force assistance, and humanitarian assistance.
Combat Operations
The primary role for the Army and Marines in the Indo-Pacific is the conduct of ground combat
operations should hostilities be initiated in the region. Such operations could range from high-
intensity force-on-force combat operations to counterinsurgency operations. How Army and
Marine forces would be employed in this role is envisaged by existing combatant command
operational plans and directives from the National Command Authority (NCA). Unlike Japan and
the Republic of Korea, the United States has no meaningful military presence in Taiwan, nor a
mutual security agreement. Given Taiwan’s geography and proximity to mainland China and
ambiguous security commitments, a great deal of uncertainty exists regarding the role of U.S.
ground forces. One author suggests that U.S. ground forces—the Army in particular—would face
an “uncomfortable reality” should a conflict over Taiwan occur:
There is a good chance that the role U.S. decisionmakers will ask the Army to play in this
conflict is not what has been presented so far: lobbing missiles or “advising” Taiwanese
military units. Instead, troops may find themselves either defending the island from a
Chinese invasion or even helping retake Taiwan after China (due to proximity and first-
mover advantages) wins the initial high-tech struggle.70
If the conflict happens as described, the author suggests the Army should shift its focus in terms
of doctrine, force structure, and modernization to “defending or retaking territory,” including
conducting large-scale amphibious landings (likely including Marines) to retake Taiwan—

68 Australian Army, “Ten years of Marine Rotational Force – Darwin,” November 16, 2021, https://www.army.gov.au/
our-news/media-releases/ten-years-marine-rotational-force-darwin, accessed April 15, 2022.
69 Australian Department of Defense, https://defence.gov.au/Initiatives/USFPI/Home/MRF-D.asp, accessed March 11,
2022.
70 Jacquelyn Schneider, “The Uncomfortable Reality of the U.S. Army’s Role in a War over Taiwan,” War on the
Rocks, November 30, 2021.
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operations considered beyond current U.S. capabilities.71 Others argue, however, that the defense
of territory is a core U.S. Army mission for which it is trained and equipped and that DOD
leadership is comfortable with the current ability of U.S. ground forces to execute combat
operations in the region.72
Directly related to combat operations is the Army’s role as an Executive Agent73 as established
under Title 10, §7013b. Under this provision the Army provides the following support to other
services:
 Land-based air and missile defense;
 Fire support;
 Base defense;
 Transportation;
 Fuel distribution;
 General engineering;
 Intra-theater medical evacuation;
 Logistics management;
 Communications;
 CBRN defense; and
 Explosive Ordnance Disposal.74
The aforementioned support provided by the Army to the other services is arguably critical to the
successful conduct of joint combat operations. In this regard, the Army’s ability to provide this
type of support in the full range of conflict scenarios may be considered equally important as its
ability to provide direct combat power.
Deterrence
Ground forces may play a key role in deterring potential adversaries from acting against the
United States and its allies. In theory, the strategic application deterrence operations is intended to
… convince adversaries not to take actions that threaten U.S. vital interests by means of
decisive influence over their decision-making. Decisive influence is achieved by credibly
threatening to deny benefits and/or impose costs, while encouraging restraint by
convincing the actor that restraint will result in an acceptable outcome ... Deterrence
requires a national strategy that integrates diplomatic, informational, military, and
economic powers.75
While all armed services participate in deterrence operations, a 2022 RAND analytical study
conducted for the U.S. Army, “Understanding the Deterrent Impact of U.S. Forces Overseas,”

71 Ibid.
72 Observation provided to CRS by the Director, Center for National Defense, Davis Institute for National Security and
Foreign Policy, The Heritage Foundation, April 20, 2022.
73 Executive Agent refers to a delegation of authority from the Secretary of Defense to service secretaries or combatant
commanders to provide specific, mostly administrative, support to other U.S. Government agencies or service
components.
74 ATP-93, Theater Army Operations, August 2021, p. 4-3.
75 Department of Defense, Deterrence Operations; Joint Operating Concept, Version 2.0, December 2006, p. 3.
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found that there was “the clearest evidence for the deterrent impact of heavy ground forces and
little, if any, evidence for the deterrent impact of air and naval forces.”76 Additional findings
included that
 there was “consistent evidence for the deterrent effects of heavy ground forces
and air defense capabilities, especially when deployed in the general theater of
interest but not necessarily on the front lines of a potential conflict”;77
 there “was evidence that light ground forces, particularly when deployed directly
inside the borders of the partner or ally being threatened, may be associated with
a higher risk of low-intensity militarized disputes, but we do not find similar
evidence of this risk for heavy ground forces in our statistical models”;78 and
 the “presence of U.S. forces in a particular country carries both a financial and an
opportunity cost. Forces deployed in one location may be less available for
contingencies elsewhere.”79
The findings and the results of RAND’s analysis suggest that U.S. ground forces could play a
leading role in deterrence in the Indo-Pacific region. In recent testimony, the Commander of
USINDOPACOM noted that
U.S. force posture is a warfighting advantage in USINDOPACOM’s operational design. A
force posture west of the International Date Line provides defense in-depth that enables the
Joint Force to decisively respond to contingencies across the region. More distributed
combat power increases survivability, reduces risk, and enables the transition from defense
to offense quickly should deterrence fail. Forward-based and rotational Joint forces armed
with the right capabilities are the most credible way to demonstrate resolve, assure allies
and partners, and provide the President and Secretary with multiple options.80
Expanding on the concept of force presence, the Commandant of the Marine Corps, General
David Berger, reportedly suggested,
The expanse of the Indo-Pacific region and layered Chinese defensive systems have put a
premium on systems that can hold an adversary hostage from a distance. However, there
is no substitute for positioning some forces close to an enemy.81
Such forward forces, as described by General Berger, would likely be comprised of U.S. ground
forces as air and naval forces have a limited on-site presence based on their inherent operational
capabilities.
Security Force Assistance (SFA)
The Joint Chiefs of Staff (JCS) defines security force assistance (SFA) as

76 Bryan Frederick, Stephen Watts, Matthew Lane, Abby Doll, Ashley L. Rhoades, Meagan L. Smith, “Understanding
the Deterrent Impact of U.S. Forces Overseas,” RAND Corporation, 2020, p. xiv.
77 Ibid., p. xvii.
78 Ibid., p. 142.
79 Ibid.
80 Statement of Admiral John C. Aquilino, U.S. Navy, Commander, U.S. Indo-Pacific Command before the House
Armed Services Committee on U.S. Indo-Pacific Command Posture, March 9, 2022, p. 14.
81 Valerie Insinna, “Top American Generals on Three Key Lessons Learned from Ukraine,” Breaking Defense.com,
March 11, 2022.
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[t]he set of DOD activities that support the development of the capacity and capability of
foreign security forces and their supporting institutions. Foreign Security Forces include
not only military forces, but also police, border forces, and other paramilitary organizations
at all levels.82
DOD further defines SFA activities:
SFA activities shall be conducted primarily to assist host countries to defend against
internal and transnational threats to stability. However, the Department of Defense may
also conduct SFA to assist host countries to defend effectively against external threats;
contribute to coalition operations; or organize, train, equip, and advise another country’s
security forces or supporting institutions.83
Security force assistance is said to have a mixed record of success, with Iraq and Afghanistan
being characterized by some as “high profile failures.”84 Other SFA operations, such as those
initiated in 2001 with Philippines to assist in combating terrorism and the 2002 Georgia Train and
Equip Program (GTEP), are considered by some as “successes”85 whereas the impact of U.S.
military training and equipment and weapons provided to Ukraine has yet to be fully assessed.
Army and Marine units typically focus on training, equipping, and advising as part of SFA, and
these activities are generally viewed as an important way to “build partner capacity” with other
counties. In addition, multinational training exercises have a role in SFA. Such exercises can
improve interoperability between militaries and serve as a deterrent to regional aggression.
While conventional Army and Marine units continue to conduct SFA activities, the Army and
Marines have developed specialized SFA units and organizations. The Army has created six
SFABs to provide regionally focused SFA support to Geographic Combatant Commanders.86 The
5th SFAB, stationed at Joint Base Lewis McChord, WA, is dedicated to USINDOPACOM. The
Army National Guard also participates in SFA, primarily through the State Partnership Program
(SPP).87 Established by Title 10 §341, SPP is a DOD security cooperation program managed and
administered by the Chief, National Guard Bureau and conducted by the Geographic Combatant
Commanders, supported by the National Guard of the states and territories.88 As of January 1,
2022, thirteen Indo-Pacific nations were involved in SPP activities with units from the Army
National Guard.89
The Marines also are involved in SFA activities. In October 2011, the Marines established the
Marine Corps Security Cooperation Group to

82 Joint Chiefs of Staff, https://www.jcs.mil/Directorates/J7-Joint-Force-Development/JCISFA/, accessed March 13,
2022.
83 Department of Defense Instruction Number 5000.68, Security Force Assistance (SFA), October 27, 2010, p. 2.
84 Renanah Joyce, Max Margulies and Tucker Chase, “The Future of U.S. Security Force Assistance,” Modern War
Institute at West Point, November 23, 2021.
85 United States Special Operations Command, Security Force Assistance Introductory Guide, July 28, 2011, p. 3.
86 For additional information on Security Force Assistance Brigades (SFABs), see CRS In Focus IF10675, Army
Security Force Assistance Brigades (SFABs), by Andrew Feickert.
87 For additional information on the State Partnership Program see CRS Report R41957, The National Guard State
Partnership Program: Background, Issues, and Options for Congress, by Lawrence Kapp and Nina M. Serafino.
88 Army National Guard Fact Sheet, at https://www.nationalguard.mil/Portals/31/Resources/Fact%20Sheets/State-
Partnership-Program-SPP-Fact%20Sheet-update.pdf, accessed April 25, 2022.
89 Army National Guard Fact Sheet, at https://www.nationalguard.mil/Portals/31/Documents/J-5/InternationalAffairs/
StatePartnershipProgram/National-Guard-State-Partnership-Program-Map-(1-Jan-22).pdf, accessed April 25, 2022.
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[e]xecute and enable Security Cooperation (SC) programs, training, planning, and
activities in order to ensure unity of effort in support of USMC and Regional Marine
Component Command (MARFOR) objectives and in coordination with the operating
forces.90
In September 2021, the Marine Corps Security Operations Group was deactivated in accordance
with the Commandant’s Planning Guidance and Force Design 2030.91 Although this group was
deactivated, the Marines have been and are involved in a wide array of long-term SFA activities
throughout the Indo-Pacific region.92
Humanitarian Assistance (HA)
Humanitarian assistance is a DOD-wide mission and is of particular importance in the Indo-
Pacific region. One report from 2019 notes that
 worldwide, the Indo-Asia-Pacific is the region most prone to disasters, and since
1970 disasters there have killed 2 million people, or 57% of the global death toll
from disasters;
 USINDOPACOM was called upon to support at least 36 foreign disaster
responses in the region from June 1991 to June 2019; and
 U.S. military forces have been called upon to support disaster relief efforts in the
USINDOPACOM AOR each year since 2004.93
Recognizing the importance of the HA mission, in 1994 Congress established the Center for
Excellence in Disaster Management & Humanitarian Assistance (CFE-DM)94 as a DOD
organization that reports directly to USINDOPACOM and is located at Joint Base Pearl Harbor-
Hickam, Hawaii. U.S. military forces in the region from all services can be involved in HA
operations and are responsible for supporting other U.S. government agencies in HA operations.
Because of the frequency of disasters, many of the exercises conducted between U.S. forces and
regional military forces focus on HA scenarios. The Army and Marines play a central role in HA
operations and can provide engineering, medical, logistics, and communications capabilities,
among other things.
The Indo-Pacific and Changes to Army and Marine
Corps Operational Concepts
In recognition of the requirements set forth in national security and military strategies, and
potentially in response to the emphasis placed on the role of the U.S. Navy and Air Force in the
Indo-Pacific, the Army and Marine Corps are modifying their operational concepts.95 For the

90 Marine Corps Security Cooperation Group, at https://www.mcscg.marines.mil/, accessed March 13, 2022.
91 Marine Corps Security Cooperation Group Deactivation Ceremony, at https://www.dvidshub.net/video/812468/
marine-corps-security-cooperation-group-deactivation-ceremony, accessed March 13, 2021.
92 CRS meeting with Marine Corps Staff, March 31, 2022.
93 Center for Excellence in Disaster Management & Humanitarian Assistance, USINDOPACOM Foreign Disaster
Response in the Indo-Asia-Pacific - June 1991 – June 2019, 2019, p. 4.
94 10 U.S.C. 182 - Center for Excellence in Disaster Management and Humanitarian Assistance, P.L. 105-85.
95 The U.S. military defines a “Concept of Operations” as a verbal or graphic statement that clearly and concisely
expresses what the joint force commander intends to accomplish and how it will be done using available resources. See
Joint Chiefs of Staff, Joint Publication 1-02, Department of Defense Dictionary of Military and Associated Terms,
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Army, this concept is referred to as “Multi-Domain Operations (MDO),” and for the Marine
Corps, it is referred to as “Stand-in Forces.”
Army Multi-Domain Operations (MDO)96
MDO describes how the Army, as part of the Joint Force, plans to counter and defeat a near-peer
adversary, such as China or Russia, that is capable of contesting the U.S. military in all domains
(air, land, maritime, space, and cyberspace) in both competition and armed conflict. While ground
combat forces in the Indo-Pacific Theater could play a part in defeating enemy forces, MDO
emphasizes the role that long-range precision fires (LRPF)—artillery and missiles—could play in
attacking both land-based and naval targets.97
Some argue, however, that the threat and challenges posed by both Russia and China may, in the
end, be so divergent that one operational concept such as MDO might not be sufficient to
adequately address both Russia and China and, as such, the Army may need to develop
capabilities—formations and equipment—tailored to each individual threat. A study by the
Heritage Foundation contends
Russia is ground centric, seeking to control the air and contest the sea and space from the
land, while China is air and maritime centric. Especially as time passes and the “boat moves
away from the dock,” it is inevitable that China’s and Russia’s capabilities—and the threats
they pose—will increasingly diverge. The Army has not been confronted with the need to
conceptualize a fight against two near-peer competitors since the development of the
Rainbow plans in the 1930s. Indeed, even today some Chinese capabilities already exceed
those of Russia. For the time being, the Army should form a “hybrid” best of breed threat,
but must be prepared for the eventual time when China and Russia present such a diversity
of capabilities and techniques that they must be addressed separately, perhaps with
different operational concepts.98
Taken further, it is possible that in some cases, MDO might be a sufficient operational approach
for some threats while an inadequate approach against other potential threats.
Marine Corps Expeditionary Advanced Base Operations (EABO)
and Stand-in Forces (SIFs)99
In February 2021, the Marines introduced a new operational concept: Expeditionary Advanced
Base Operations (EABO). At the conceptual level, EABO envisions
the employment of mobile, low-signature, persistent, and relatively easy to maintain and
sustain naval expeditionary forces from a series of austere, temporary locations ashore or

2011, p. 72.
96 For additional information on Multi-Domain Operations, see CRS Insight IN11019, The U.S. Army and Multi-
Domain Operations, by Andrew Feickert.
97 For additional information on long-range precision fires, see CRS Report R46721, U.S. Army Long-Range Precision
Fires: Background and Issues for Congress, by Andrew Feickert.
98 Thomas W. Spoehr, “Rebuilding America’s Military Project: The United States Army,” The Heritage Foundation,
Special Report, No. 215, August 22, 2019, p. 34.
99 Information in this section, unless otherwise noted, is taken from U.S. Marine Corps, “A Concept for Stand-in
Forces,” November 2021.
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inshore within a contested maritime area in order to conduct sea denial, support sea control,
or enable fleet sustainment.100
In November 2021, the Marines introduced “A Concept for Stand-in Forces,” providing
additional context and operational examples for EABO. The SIF concept also proposes a
multidomain approach to operations similar to the Army’s. The Marines acknowledge that
[t]he People’s Republic of China (PRC) is the pacing challenge for the joint force; thus,
while the concept [SIF] is applicable globally, the INDOPACOM area of responsibility is
appropriately the focus of the Stand-in Forces concept.101
SIFs are considered a conceptual shift from the resource-intensive, land-centric focus of previous
decades, where Marine and Army units performed largely interchangeable operational missions,
to a more naval and expeditionary focus. The Marines described the central idea of SIFs as
follows:
 SIFs are small, lethal, low-signature, mobile, simple-to-maintain-and-sustain
forces designed to operate across a contested area as the leading edge of a
maritime defense-in-depth intended to disrupt the plans of a potential or actual
adversary.
 SIFs can be composed of elements from the Marine Corps, Navy, Coast Guard,
special operations forces, interagency, and allies and partners.
 SIFs can deter potential adversaries by establishing the forward edge of a
maritime defense-in-depth to deny adversaries freedom of action.
 SIFs’ primary function is to help the fleet and joint force with reconnaissance and
to deter adversarial reconnaissance in all phases of operations.
 When directed, SIFs conduct sea denial operations, especially near maritime
chokepoints. They do so through the use of organic sensors and weapon systems
and by integrating organic capabilities with naval and joint all-domain
capabilities.
 SIFs are to have sufficient organic-maneuver and offensive capability to gain a
position of advantage by securing, seizing, and controlling contested key
maritime terrain in support of sea denial operations.102
How the Army and Marines Plan to Fulfill Their
Operational Roles
In planning for operations in the Indo-Pacific region, the Army and Marines envision somewhat
different roles than their traditional sustained land combat and large-scale amphibious assault
roles.

100 Headquarters Marine Corps, “Tentative Manual for Expeditionary Advanced Base Operations,” February 2021.
101 U.S. Marine Corps, “A Concept for Stand-in Forces,” November 2021, p. 2.
102 Ibid., p. 4.
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Army
Army leaders argue that, in addition to its traditional land combat role, LRPF in the Indo-Pacific
region will increase its utility to the Joint Force.103 As part of this effort, the Army is seeking to
upgrade current artillery and missile systems, develop new longer-range cannons and hypersonic
weapons, and modify existing air- and sea-launched missiles and cruise missiles for ground
launch by Army units. One unique aspect of the Army’s LRPF effort is that in addition to using
these systems for engaging land targets, the Army also envisions using them to engage naval
targets.
In December 2021, Secretary of the Army Christine Wormuth further defined the Army’s role in
the Indo-Pacific region.104 Calling the Army the “linchpin service,” she reportedly identified six
core tasks for the Army in the Indo-Pacific:
 establishing, building, securing, and protecting staging areas and joint operating
bases for air and naval forces in theater;
 providing integrated air and missile defense;
 sustaining the Joint Force with logistics and communications;
 running command and control at multiple levels;
 providing ground-based long-range fires; and
 employing Army ground maneuver forces.105
Secretary Wormuth noted that in a nondirect combat supporting role, the Army would be
responsible for building and defending bases in the Pacific, providing command and control, and
establishing and sustaining theater-wide logistics, including maintaining munitions stockpiles and
forward-arming and refueling points.106
Marines
The Center for Strategic and International Studies (CSIS) summarizes the Marines’ role in the
Indo-Pacific in terms of how forces are to operate and avoid being targeted. The Marines contend
that central to the vision
is the ability to operate within an adversary’s (read China’s) bubble of air, missile, and
naval power (which the Marine Corps calls the weapons engagement zone, or WEZ). The
concept is that the Marine Corps will be a “stand-in force” that will operate within this
WEZ, not a stand-off force that must start outside and fight its way in. As the guidance
states: “Stand-in forces [are] optimized to operate in close and confined seas in defiance of
adversary long-range precision ‘stand-off capabilities.’” This requires developing “low
signature, affordable, and risk worthy platforms” because existing ships and aircraft are the
opposite—highly capable but expensive, few, and highly visible.

103 For additional information on Army long-range precision fires, see CRS Report R46721, U.S. Army Long-Range
Precision Fires: Background and Issues for Congress, by Andrew Feickert.
104 Information in this section is taken from Matthew Beinart, “Army May Be Linchpin Service for the Joint Force in
Potential Fight with China, Wormuth Says,” Defense Daily, December 2, 2021; Andrew Eversden, “Wormuth: Here’s
the Army’s Role in a Pacific Fight,” Breaking Defense, December 1, 2021; and C. Todd Lopez, “For Contingencies in
Indo-Pacom, Army Will Serve as ‘Linchpin’ for Joint Force,” DOD News, December 1, 2021.
105 Ibid.
106 Ibid.
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Another element of the new concept is “distributed operations,” the ability of relatively
small groups to operate independently rather than as part of a large force, as in previous
wars. “We recognize that we must distribute our forces ashore given the growth of
adversary precision strike capabilities ... and create the virtues of mass without the
vulnerabilities of concentration.” Thus, small Marine forces would deploy around the
islands of the first island chain and the South China Sea, each element having the ability to
contest the surrounding air and naval space using anti-air and anti-ship missiles.
Collectively, these forces would attrite Chinese forces, inhibit them from moving outward,
and ultimately, as part of a joint campaign, squeeze them back to the Chinese homeland.
A third element was institutional: the Marine Corps would leave sustained ground combat
to the Army and focus on the littorals. Ground wars in the Middle East, North Korea, and
Europe would be Army responsibilities.107
The Marines also plan to expand their LRPF.108 In particular, the Marines intend to field mobile
anti-ship missiles. The Navy-Marine Expeditionary Ship Interdiction System (NMESIS) uses the
Marines’ High Mobility Artillery Rocket System (HIMARS) and the Naval Strike Missile (NSM)
mounted on the chassis of a remotely operated Joint Light Tactical Vehicle (JLTV).
Force Structure Changes
The Army and Marines have undertaken a variety of force structure changes to better fulfill their
roles as stipulated by national security and military strategies, as well as to support both Joint and
service-specific operational concepts. With DOD describing China as the “pacing threat,” these
force structure changes are informed by how the Army and Marines believe they will compete
against potential adversaries in the Indo-Pacific and, if necessary, conduct combat operations in
the region.
The Army’s AimPoint and Army 2030 Force Structure Initiatives109
In 2020, the Army undertook the AimPoint Force Structure initiative to build the force structure
needed to implement the 2018 National Military Strategy’s new focus on China and Russia. As
part of AimPoint, the Army plans to create five Multi-Domain Task Forces (MDTF).110 MDTFs
are based on a Field Artillery (FA) brigade and augmented with an intelligence, information
operations, cyber, electronic warfare, and space (I2CEWS) detachment. The first MDTF was
established as a pilot program in 2017. It is stationed at Joint Base Lewis McChord, WA, and is
assigned to U.S. Army Pacific Command. A second MDFT was activated in Europe in 2021 and
the Army plans to establish an additional Indo-Pacific-focused MDTF in the future.
In January 2022, Army officials reportedly redesignated the Aim Point initiative (which had been
renamed “Way Point 2028” in 2021) to “Army 2030.”111 Under Army 2030, the Army envisions
either redesignating existing divisions or creating new divisions into five new types of divisions:

107 Mark F. Cancian, “The Marine Corps’ Radical Shift Toward China,” Center for Strategic and International Studies,
March 25, 2020.
108 Information in this section is from David B. Larter, “To Combat the China Threat, U.S. Marine Corps Declares
Ship-Killing Missile Systems Its Top Priority,” DefenseNews.com, March 5, 2020.
109 For additional information on Army force structure initiatives, see CRS In Focus IF11542, The Army’s AimPoint
and Army 2030 Force Structure Initiatives, by Andrew Feickert.
110 For addition information on Multi-Domain Task Forces, see CRS In Focus IF11797, The Army’s Multi-Domain
Task Force (MDTF), by Andrew Feickert.
111 Ethan Sterenfeld, “Waypoint 2028 Becomes Army 2030,” InsideDefense.com, January 25, 2022.
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 Standard Light,
 Standard Heavy,
 Penetration,
 Joint Force Entry Air Assault, and
 Joint Force Entry Airborne.
It is not known if the five new division types were created with Indo-Pacific operational
requirements in mind or what roles they might play in the region. These new unit types may have
new capabilities as well.
Marine Corps Force Design 2030112
On March 23, 2020, the U.S. Marine Corps (USMC) announced a major force design initiative
scheduled to occur over the next 10 years: “Force Design 2030.”113 As part of this initiative, the
Marines plan to redesign the force for naval expeditionary warfare and to better align with the
National Defense Strategy, in particular, its focus on strategically competing with China and
Russia. The Marines intend to eliminate or reduce certain types of units and eliminate some
military occupational specialties (MOS). The Marines also plan to reorganize higher echelon
Marine formations and to reduce forces by 12,000 personnel by 2030. Selected major unit
eliminations/reductions include
 eliminating all Tank Battalions,
 reducing the size of and number of Infantry battalions from 24 to 21,
 reducing the number of Cannon Artillery Batteries from 21 to 5,
 reducing the number of Amphibious Vehicle Companies from 6 to 4, and
 eliminating a number of Medium Tiltrotor Squadrons, Heavy Helicopter
Squadrons, Light-Attack Helicopter Squadrons, and Wing Support Groups.
The Marines also plan to establish three Marine Littoral Regiments (MLRs) organized, trained,
and equipped to accomplish sea denial-and-control missions. The 3rd MLR—the redesignated 3rd
Marine Regiment—is based in Hawaii, and plans call for converting two other regiments, the 4th
and 12th Marine Regiments—currently stationed in Japan—into MLRs that are to be stationed in
Japan and Guam. Each MLR is planned to consist of about 1,800 to 2,000 Marines and sailors
and include three main elements; a Littoral Combat Team (LCT), a Littoral Anti-Air Battalion,
and a Littoral Logistics Battalion.
The Marines’ Force Design 2030 has been described as “a campaign of change as significant as
any since the end of the Vietnam War.”114 While Marine Corps leadership has, for the most part,
embraced Force Design 2030, some have suggested there are fundamental problems with its
approach. One analyst contends that “the restructuring has been criticized for focusing too much
on a maritime campaign in the Western Pacific, ignoring global conflicts, and relying on

112 For additional information on Marine Force Design 2030, see CRS Insight IN11281, New U.S. Marine Corps Force
Design Initiative: Force Design 2030, by Andrew Feickert.
113 Ibid. All information in this section is taken directly from CRS Insight IN11281, New U.S. Marine Corps Force
Design Initiative: Force Design 2030, by Andrew Feickert.
114 Walker Mills and Timothy Heck, “The Marine Corps Should Look to the Army for Lessons Learned on Force
Design,” The Modern War Institute at West Point, January 27, 2022, p. 1.
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unproven operational concepts.”115 One former senior Marine Corps officer, retired LTG Paul K.
Van Riper, offered his observations in an editorial:
Marine Corps soon will no longer be the ready combined-arms force that our nation has
long depended upon when its interests were threatened. It will be a force shorn of all its
tanks and 76% of its cannon artillery, and with 41% fewer Marines in its infantry battalions.
To make the situation even worse, there will be 33% fewer aircraft available to support
riflemen on the ground. These divestures were and are being made to provide the resources
for three Marine littoral regiments, designed to support naval campaigns for sea denial and
sea control by firing anti-ship missiles.
So, the Marine Corps will trade its combined-arms flexibility for a very specialized mission
that the U.S. Army already can provide in greater numbers than the Marine Corps ever will.
Moreover, for as long as eight years the Corps will be neither the powerful forcible-entry
force in readiness it has been for decades nor the specialized anti-ship force of the future—
neither fish nor fowl—which will seriously jeopardize national security. This is a risk not
worth taking. In the end the Corps will have more space experts, cyber warriors, influence
specialists, missileers and others with unique skills—many of which already are provided
by other elements of the joint force.116
While there have been critics of Force Design 2030, there have also been a number of
supporters,117 including some Members of Congress.118 Congressional propoenents contend that
“Force Design 2030 realigns priorities towards investments in new technologies, formations, and
capabilities better suited for the Marine Corps’ mission and expeditionary nature.”119
Weapon Systems and Equipment
As they develop new operational concepts and force designs, the Army and Marine Corps are
pursuing weapons systems and equipment to support respective operational concepts and to equip
units under development. The following sections highlight selected weapon systems and
equipment being sought by the Army and Marines.
Army
Given the limited range of Army ground combat systems and the geographic expanse of the Indo-
Pacific region, the primary means by which the Army can contribute to joint operations, other
than force-on-force ground combat, is through LRPF. As such, the Army is focusing primarily on
LPRF weapon systems and equipment, which consists of upgrades to current artillery and missile
systems, development of new longer-range cannons and hypersonic weapons, and modification of

115 Mark F. Cancian, “U.S. Military Forces in FY2022: Marine Corps,” Center for Strategic and International Studies,
November 2021, p. 2.
116 Lt. Gen. Paul K. Van Riper (Retired), “Jeopardizing National Security: What is Happening to Our Marine Corps?,”
Marine Corps Times, March 21, 2022.
117 For example, see Tom Rogan, “The Marines Are Reforming to Prepare for War With China; General David H.
Berger Seeks a More Agile Force,” Wall Street Journal, April 4, 2022; Benjamin Jensen, “The Rest of the Story:
Evaluating the U.S. Marine Corps Force Design 2030,” War on the Rocks, April 27, 2020; and General Eric Smith,
USMC, “Stand-In Forces: Adapt or Perish,” Proceedings, U.S. Naval Institute, vol. 148, April 2022.
118 Dear Colleague Letter to Chair and Ranking Member of the Senate Committee on Appropriations and Chair and
Ranking Member of the House Committee on Appropriations urging budgetary support for Marine Corps Force Design
2030, May 27, 2022.
119 Ibid.
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existing air- and sea-launched missiles and cruise missiles for ground launch by Army units.120
The Army is developing three ground-based, long-range systems: (1) the Long-Range Hypersonic
Weapon (LRHW),121 (2) the Mid-Range Capability System (a ground-based, anti-ship missile
system armed with Navy SM-6 or Tomahawk cruise missiles),122 and (3) the Precision Strike
Missile (PrSM), which can be fired from existing Army Multiple Launch Rocket Systems
(MLRS) or Army and Marine Corps High Mobility Artillery Rocket Systems (HIMARS).
The LRHW is considered a particularly important system in the Indo-Pacific context.123 This
weapon consists of a ground-launched missile (with a reported range of 1,725 miles) equipped
with a hypersonic glide body and associated transport, support, and fire control equipment.124
According to the Army,
Hypersonic missiles that can travel well over 3,800 miles per hour. They can reach the top
of the Earth’s atmosphere and remain just beyond the range of air and missile defense
systems until they are ready to strike, and by then it’s too late to react. Extremely accurate,
ultrafast, maneuverable and survivable, hypersonics can strike anywhere in the world
within minutes.125
Organizationally, each MDTF reportedly is to have a Long-Range Fires Battalion consisting of
one LRHW battery with four launchers each having two missiles apiece, one Mid-Range
Capability Battery, and one PrSM HIMARs battery.126 Under the Army’s current force construct,
a total of six batteries (three batteries per MDTF) of these missiles would be dedicated to the
Indo-Pacific region.
Marines127
In a February 2022 media roundtable, the Assistant Commandant of the Marine Corps discussed
emerging technologies that would be deployed in the Indo-Pacific, primarily to support MLRs.128
As previously noted, one such system is the Navy-Marine Expeditionary Ship Interdiction System
(NMESIS). Is this role, NMESIS would enable MLR units to conduct anti-ship strikes and
possibly gain sea control by means of threatening enemy ships. Another system is the MQ-9A
Reaper Unmanned Aerial Vehicle (UAV), which is intended to provide extended range
surveillance, intelligence collection, and reconnaissance. The MQ-9A could potentially be used to
provide information to both the Joint Force and Marines and could possibly be used to help direct
NMESIS strikes. A third system is the Ground/Air Task Oriented Radar (G/ATOR), which is

120 For additional information on long-range precision fires, see CRS Report R46721, U.S. Army Long-Range Precision
Fires: Background and Issues for Congress, by Andrew Feickert.
121 For additional information on the Long-Range Hypersonic Weapon, see CRS In Focus IF11991, The U.S. Army’s
Long-Range Hypersonic Weapon (LRHW), by Andrew Feickert.
122 For additional information on the Mid-Range Capability System, see CRS In Focus IF12135, The U.S. Army’s Mid-
Range Capability (MRC) Weapon System, by Andrew Feickert.
123 For additional information on the Long-Range Hypersonic Weapon (LRHW), see CRS In Focus IF11991, The U.S.
Army’s Long-Range Hypersonic Weapon (LRHW), by Andrew Feickert.
124 For additional information on hypersonic weapons, see CRS In Focus IF11459, Defense Primer: Hypersonic Boost-
Glide Weapons, by Kelley M. Sayler and Amy F. Woolf.
125 Lt. Gen. L. Neil Thurgood, “Hypersonics by 2023,” Army News Service, September 4, 2019.
126 Ethan Sterenfeld, “Army Plans Three Hypersonic Batteries in MDTFs,” InsideDefense.com, February 23, 2022.
127 Information in this section is taken from Megan Eckstein, “Standup of Marine Littoral Regiment Will Usher New
Gear into Pacific Theater,” Defense News, February 28, 2022.
128 Ibid.
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intended to be part of the theater communications architecture and to facilitate data sharing with
the Marines, Navy, and the rest of the Joint Force. According to the Marines,
The G/ATOR’s interoperability with Naval systems and transportability make it a critical
component to achieving Force Design [2030].... Initially fielded in 2018, G/ATOR can
support various missions, depending on the “block” of software used on a single hardware
platform. G/ATOR Block 1 provides air defense and surveillance capabilities, while Block
2 supports artillery operations.129
The final two systems sought by Marine leadership are a Marine-owned and -operated Long-
Range Unmanned Surface Vessel130 and the Navy’s Light Amphibious Warship (LAW),131 both of
which are intended to transport Marines, supplies, and equipment in littoral regions.132 Some are
concerned, however, that developing and procuring the LAW may be challenging, and that it may
not be available until 2025.133
The Pacific Deterrence Initiative (PDI)
On an annual basis, primarily through the National Defense Authorization Act and the Defense
Appropriations Act, Congress establishes policy and provides funding for the services and matters
pertaining to the Indo-Pacific region. In the FY2021 National Defense Authorization Act (NDAA;
P.L. 116-283, §1251), Congress created the PDI reportedly to “better understand what the
Pentagon was spending in the Indo-Pacific region and to change the composition of that
spending.”134 Concerned that “the Pentagon’s budget justification books provide minimal
information about how its spending aligns to specific theaters, threats or missions,” the PDI was
seen as a means to pull “information together in a consolidated budget display,” and “to increase
transparency, identify key Indo-Pacific investments, and enable Congress to track, assess and
adjust those efforts over time.”135
DOD’s FY2022 PDI budget request called for $5.1 billion to be allocated between the Navy, Air
Force, Missile Defense Agency, and the Office of the Secretary of Defense, but no funds were
requested under PDI for the Army.136 Categories for PDI funding included Force Design and
Posture, Exercises, Experimentation, and Innovation, Joint Force Lethality, and Strengthen
Alliances and Partnerships.137 The FY2022 NDAA Joint Explanatory Statement “identified
approximately $7.1 billion in investments that support and attempt to improve the current posture,

129 Ashley Calingo, “Inside Acquisition: How the G/ATOR Modernizes the Corps for the Future Fight,” Office of
Public Affairs and Communication, Marine Corps Systems Command, July 14, 2021.
130 For additional information on this system, see CRS Report R45757, Navy Large Unmanned Surface and Undersea
Vehicles: Background and Issues for Congress, by Ronald O'Rourke.
131 For information on the Light Amphibious Warship, see CRS Report R46374, Navy Light Amphibious Warship
(LAW) Program: Background and Issues for Congress, by Ronald O'Rourke
132 For additional information on the Light Amphibious Warship, see CRS Report R46374, Navy Light Amphibious
Warship (LAW) Program: Background and Issues for Congress, by Ronald O'Rourke.
133 Todd South, “Back to Ship: Marines Need Ships to Fight. Will They Get Them?” Military Times, March 24, 2022,
and “Marines Will Have to Wait Until 2025 for Light Amphibious Warship,” Marine Corps Times, March 28, 2022.
134 Dustin Walker, “Pacific Deterrence Initiative: A Look at Funding in the New Defense Bill, and What Must Happen
Now,” Defense News, December 15, 2021.
135 Ibid.
136 Pacific Deterrence Initiative, Department of Defense Budget, Fiscal Year (FY) 2022, Office of the Under Secretary
of Defense (Comptroller), May 2021.
137 Ibid.
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capabilities, and activities of U.S. forces in the Indo-Pacific region,” and included funding for
Army Procurement, Operations and Maintenance, and Military Construction.138
DOD’s FY2023 PDI budget request calls for $6.1 billion “in critical investments [to] include
integrated fires, new missile warning and tracking architecture, construction to enable enhanced
posture, funding for defense of Guam, and multinational information sharing, training, and
experimentation.”139
Potential Issues for Congress
The Role of U.S. Ground Forces in the Indo-Pacific
As discussed above, the Army and Marines have four primary roles in the Indo-Pacific: combat,
deterrence, security force assistance, and humanitarian assistance. In terms of the latter two
roles—security force assistance and humanitarian assistance—it can be argued that the roles both
services play in supporting the region’s allied and partner ground forces and providing
humanitarian assistance ashore cannot be fulfilled by the Navy and Air Force. Furthermore, while
somewhat intangible, these two roles are seen as important in building and maintaining good
relations with regional partners and allies, and in furthering security relationships with nonaligned
nations in the region. Given the importance of these two roles, Congress might consider whether
additional Army and Marine resources should be devoted to security force assistance and
humanitarian assistance?
In terms of deterrence, RAND’s 2022 study conducted for the Army seems to reinforce the
argument that heavy ground forces and air defense units provide a greater deterrent effect than air
and naval forces. If so, Congress might consider if the Army and Marines should play a greater
role in deterrence operations in the Indo-Pacific region.
In terms of regional combat roles, two of the scenarios for ground combat—the defense of the
ROK from a DPRK attack and ground operations in response to a PRC invasion of Taiwan—
might also be a subject for Congress to discuss. Regarding the defense of the ROK, the United
States has limited ground combat forces available in theater to respond to a DPRK attack and
supposedly would deploy additional ground forces from the United States if needed. As currently
configured, U.S. ground forces seem to play a somewhat minor role in that scenario. As such,
Congress might reexamine the role of U.S. ground forces in the ROK to determine whether the
United States has the right mix, types, and quantities of ground forces to respond to a DPRK
ground attack. With the vast majority of attention being given to China-related regional security
issues, and given the unpredictability and provocations from the DPRK, such an examination
could help to ensure that Congress is fully informed on what is arguably the most likely scenario
where U.S ground forces are involved in direct combat in the region.
The role of U.S. ground forces in an invasion of Taiwan or other PRC regional aggression is less
well-defined than that of the defense of the ROK. In terms of regional Chinese aggression, if
ground combat is not a factor, the primary combat role for the Army and Marines would likely be
long-range fires against ground and naval targets, as well as regional air and missile defense of
U.S. forces and bases such as Guam. Furthermore, the Marines’ divestment of tanks, towed

138 Joint Explanatory Statement to Accompany the National Defense Authorization Act for Fiscal Year 2022, December
5, 2021, p. 280.
139 Office of the Under Secretary of Defense (Comptroller)/Chief Financial Officer, United States Department of
Defense, Fiscal Year 2023 Budget Request: Defense Budget Overview, March 2022, p. 14.
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artillery, and aircraft as part of Force Design 2030 might also have implications for the Marines’
role in force-on-force combat, particularly against an opponent with mechanized or armored
forces. As discussed above, some experts are concerned that U.S. ground forces—the Army in
particular—would face an “uncomfortable reality” in terms of its role related to Taiwan and could
be called upon instead to defend or retake territory, including by amphibious assault, that might
be beyond current U.S. military capabilities.140 The combat role for the Army and Marines in the
Indo-Pacific region raises a number of concerns about how realistic that role might be, potentially
meriting further discussion by Congress.
U.S. Ground Forces Posture in the Indo-Pacific Region
For each of the roles mentioned above, the way in which U.S. ground forces are postured in the
Indo-Pacific region is of critical concern. Posture is generally defined as forces, locations
(including large bases, forward-operating bases, and prepositioned stocks), and political
agreements concerning what those forces can do under certain conditions, including overflight
access for U.S. aircraft.141 Force posture in the Indo-Pacific region influences deterrence, dictates
what weapon systems can range targets, the air and missile defense coverage of potential ground
targets, and the actions needed to resupply and maintain forward-deployed U.S. ground forces
within range of enemy weapon systems.
Some analysts contend that “the Pentagon has been promising a more distributed and resilient
posture in the Indo-Pacific, but it has not kept that promise. Highly concentrated with few active
or passive defenses, American forces—and lives—remain dangerously vulnerable to attack.”142
Some observers within DOD and Congress reportedly advocate building up forces on Guam and
Japan and forward deploying U.S. forces in what is referred to as the first island chain that rings
China in the Western Pacific (including Japan), others are concerned that U.S. forces are not
sufficiently hardened and that forward-deployed troops would not be able to withstand “China’s
new generation of highly-capable missile and rocket forces.”143 Those concerned with the
perceived dangers of a more forward-deployed force posture favor “keeping American troops and
assets outside of China’s range, in places like Hawaii, Alaska, and California, using nascent long-
range firepower and stealth bombers capable of withstanding Chinese air defense.”144
Some observers suggest that the Pentagon and Congress should take a more active role in
resolving the Indo-Pacific force posture debate.145 Issues such as hardening facilities, developing
active and passive defense measures, and pursuing optimal locations for U.S. ground forces are
within DOD’s authority. Congress could likewise examine options regarding where forces might
be postured to best support U.S. national security and military objectives. The creation of the
Pacific Deterrence Initiative has been called a “turning point” whereby Congress—recognizing
the Pentagon’s “say-do gap” on force posture—established a mechanism for better aligning

140 Jacquelyn Schneider, “The Uncomfortable Reality of the U.S. Army’s Role in a War over Taiwan,” War on the
Rocks, November 30, 2021.
141 Chris Dougherty, “Don’t Trust the Process: Moving from Words to Actions on the Indo-Pacific Posture,” War on
the Rocks, February 23, 2022.
142 Dustin Walker, “The Pentagon is in Desperate Need of an Intervention from the Top,” War on the Rocks, January
27, 2022.
143 Jack Detsch, “Pentagon Faces Tense Fight Over Pacific Pivot,” Foreign Policy, June 7, 2021.
144 Ibid.
145 Dustin Walker, “The Pentagon is in Desperate Need of an Intervention from the Top,” War on the Rocks, January
27, 2022.
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resources to force posture needs.146 In addition to upgrading and protecting facilities throughout
the region, PDI funds could be used for forward positioning of defense material.147 While the
Army and Marine Corps both maintain and have access to prepositioned stocks148 in the region,
further investment in forward positioning of defense materials could “expand the capacity of the
U.S. military to operate in the region.”149
U.S. Ground Forces Execution of Regional Wartime Missions
The Army and Marines face a different potential combat environment in the Indo-Pacific than in
Europe or the Middle East. While conflict in Europe and the Middle East would likely involve
force-on-force ground combat, it is conceivable that conflict in the Indo-Pacific would not. In this
case, the Army and Marines’ primary contribution would be LRPF against ground and naval
targets. Although Army and Marine Corps long-range systems are based on existing systems, it is
not known if the services will acquire these systems in sufficient quantities for use in a potentially
protracted conflict. In addition, it is uncertain how these systems would be used against ground
and naval targets and how those targets would be identified and validated for attack. This is a
critical concern, particularly at extended ranges, when targets may be beyond visual identification
range and beyond the range of existing intelligence, surveillance, and reconnaissance systems
integral to the targeting process.
Army
As discussed above, in December 2021 Secretary of the Army Christine Wormuth further defined
the Army’s role in the Indo-Pacific region.150 Secretary Wormuth emphasized, in addition to
establishing and protecting operating bases, ground combat, and long-range precision fires, three
other missions:
 providing integrated air and missile defense,
 sustaining the Joint Force with logistics and communications, and
 running command and control at multiple levels.
These missions, as well as the concerns associated with them, are briefly described in the
following sections.
Air and Missile Defense
To defend Marine forces ashore against selected short-ranged air threats, the Marines rely on
short-range air defense (SHORAD) systems and depend on the Navy for missile defense. As a
result, the Army is the only service capable of providing ground-based missile defense. The Army
has, at present, 15 Patriot Battalions and 7 Terminal High Altitude Area Defense (THAAD)
batteries dedicated to missile defense. DOD’s FY2023 budget request calls for fielding an

146 Ibid.
147 Alan Tidwell, “Building a Better Partner in the Pacific,” War on the Rocks, January 28, 2022.
148 For additional information on pre-positioned stocks, see CRS In Focus IF11699, Defense Primer: Department of
Defense Pre-Positioned Materiel, by Maureen Trujillo and G. James Herrera.
149 Alan Tidwell, “Building a Better Partner in the Pacific,” War on the Rocks, January 28, 2022.
150 Information in this section is taken from Matthew Beinart, “Army May Be Linchpin Service for the Joint Force in
Potential Fight with China, Wormuth Says,” Defense Daily, December 2, 2021, and Andrew Eversden, “Wormuth:
Here’s the Army’s Role in a Pacific Fight,” Breaking Defense, December 1, 2021.
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additional THAAD battery for eight batteries.151 During testimony on May 5, 2022, the Secretary
of the Army and Chief of Staff of the Army stated the Army would add an additional Patriot
Battalion by FY2029 to enhance base defense.152
USINDOPACOM has three Patriot Battalions and two THAAD batteries.153 In addition, Patriots
and THAADs are routinely employed in U.S. European Command (USEUCOM) and U.S.
Central Command (USCENTCOM), which could affect the Army’s ability to provide additional
ground-based missile defense to INDOPACOM. Further complicating the issue is the high
operational tempo, or OPTEMPO,154 of Patriot and THAAD units. According to Army leaders,
THAAD and Patriot missile batteries “remain among the most frequently deployed units in the
service,” and there is an “acknowledged need to ease the burden on soldiers manning those
systems.”155
When considering resource limitations and the strain on soldiers crewing and maintaining Patriot
and THAAD, along with the Army’s commitment to provide integrated air and missile defense
for the entire theater, it is possible that the Army is overestimating its ability to accomplish this
mission as presently configured and resourced.
Joint Force Logistics and Communications
In addition to providing logistics and communications support to Army units in the region, the
Army, as Executive Agent, is also responsible for various types of support to other members of
the Joint Force. Secretary of the Army Wormuth noted in 2021
The Army will provide much of the secure communication network background. We will
generate intra-theater distribution networks to keep the joint force supplied from dispersed
locations, and we will maintain munition stockpiles and forward arming and refueling
points.156
Logistics pose a particular challenge to the Army due to the geography of the Indo-Pacific region,
especially given the potential for long, contested lines of communications. The United States does
not have the freedom of movement and distribution of logistics that it has had in past conflicts.
Rather, the Indo-Pacific operational environment and China’s military capabilities have given rise
to the concept of “Contested Logistics,” whereby U.S. logistics operations might be subject to
attack—kinetic and/or cyber—throughout the entire supply chain. This issue is further
complicated by Army and Marine plans for dispersed operations, including remote locations that
might not have suitable airfields or ports. Supporting these remote locations could require not

151 Office of the Under Secretary of Defense (Comptroller)/Chief Financial Officer, United States Department of
Defense, Fiscal Year 2023 Budget Request: Defense Budget Overview, March 2022, p. 10.
152 Statement by The Honorable Christine E. Wormuth, Secretary of the Army, and General James C. McConville,
Chief of Staff, United States Army, Before the Committee on Appropriations Subcommittee on Defense, United States
Senate, Second Session, 117th Congress, On The Posture of the United States Army, May 5, 2022, p. 6.
153 U.S. Army, Air and Missile Defense Vision 2028, March 2019, p. 18.
154 OPTEMPO can be defined as the rate of military operations as measured by deployments, training exercises,
temporary duty assignments, and work hours that result in a servicemember being absent from their household and
family.
155 Kyle Rempfer, “Got to Fix That: Some Unit Ops Tempos Higher Than Peaks of Afghan, Iraq Wars, Army Chief
Says,” Army Times, October 2, 2020.
156 C. Todd Lopez, “For Contingencies in Indo-Pacom, Army Will Serve as ‘Linchpin’ for Joint Force,” DOD News,
December 1, 2021.
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only multiple modes of distribution and transportation, but also a means to protect logistics
operations from attack.
Unlike combat capability, logistics capability is more difficult to define and quantify. As one
former DOD senior official observed, “the Department of Defense does a great job at running
wargames” but oftentimes “they assume away any logistics and sustainment problems, because if
you play them for real, it screws up the game.”157 To better understand how the Army plans to
fulfil its Indo-Pacific logistics responsibilities, Congress might benefit from a comprehensive
classified briefing from the Army, INDOPACOM, and U.S. Transportation Command
(USTRANSCOM) on the Army’s role and capabilities related to regional joint logistics. This
briefing could include what resources and capabilities are needed to operate in a contested
environment and how logistics support could be provided to remote locations subject to PRC
interdiction.
Command and Control at Multiple Echelons
Secretary Wormuth stated in 2021
The Army can also provide command and control capability at multiple levels to ensure
coordination and synchronization across the joint force. The Army, with its substantial
planning and operations capacity at the division and corps level, is uniquely well placed to
provide command and control for the Joint Force.158
Taken at face value, this statement appears to be more aspirational than empirical, outlining
general capabilities rather than specific of DOD policy. Given the numerous service headquarters
in and associated with the Indo-Pacific region, along with the comparable planning and
operations capabilities resident in the Navy, Air Force, and Marines, there is an element of
ambiguity associated with command and control roles and responsibilities in the Indo-Pacific. A
briefing on Indo-Pacific command and control could facilitate greater congressional
understanding of this essential function.
Marines
The Marines’ new operational concept, as conveyed in EABO, Stand-in Forces, and Force Design
2030, reflects the belief that the Marines’ mission in the Indo-Pacific can best be accomplished by
providing distributed maritime defense-in-depth through preconflict competition activities,
reconnaissance, target identification, and the provision of long-range fires against ground and
naval targets. A number of related concerns could affect the Marines’ ability to execute their
wartime mission as envisioned.
Some observers have suggested that to properly execute this strategy, the Marines would need to
have forces in position before the onset of hostilities:159
There also would be significant political hurdles to implementing such a strategy. Host
nations would have to authorize the positioning of U.S. forces on their territory

157 David Berteau, “Moving Pieces on the Chessboard: Strategy and Logistics in the Indo-Pacific,” Center for Strategic
and International Studies, November 4, 2021.
158 C. Todd Lopez, “For Contingencies in Indo-Pacom, Army Will Serve as ‘Linchpin’ for Joint Force,” DOD News,
December 1, 2021.
159 Information in this section is taken from The Maneuverist Papers, “Expeditionary Advanced Based Operations,”
Marine Corps Gazette, April 2022, p. 103.
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indefinitely.... The United States would need to make arrangements with individual states
for pre-conflict basing, and these would be difficult to arrange.160
In a sense, the Marines’ proposed operational concept for the Indo-Pacific depends on the ability
to gain access to territory, which is complicated by the fact that nations granting such access
could face economic pressure from China.161 Another concern is that adopting this operational
concept, which focuses on defeating an enemy at long distance with precision fires, could make
tactical maneuvers less relevant. For example, without this capability,
[at] some point enemy forces will penetrate the friendly anti-access barrier, and when they
do, the outnumbered and isolated small Marine units will be fighting for survival without
the benefit of cannon artillery or tank support.162
Because Marine forces are expected to remain undetected through mobility, concealment, and
maintaining a low electronic signature, security is another concern:
Any emplacement that remains in place for any period of time will start to accumulate
infrastructure.... If stand-in forces are engaged in security cooperation activities prior to
hostilities, as is envisioned, their presence will be well known to the local population. That
population almost certainly will be infiltrated with human intelligence sources.163
Logistics support is another potential challenge and would likely also play a factor in stand-in
force survivability:
Every resupply mission or other logistics contact risks giving away the expeditionary
advanced base’s (EAB) position, which is why EABs are meant to be largely self-
sustaining ... we understand that local sustainment primarily means living off the local
economy through greater operational contract support. Like security cooperation activities
do, self-sustainment presents a major operations security risk. Interactions with the local
population will expose the EAB to detection by human intelligence. EABs are likely to be
pinpointed every bit as much as if they had been detected by high-technology sensors.164
If Marine stand-in forces are identified preconflict, a major concern for some is that a PRC first
strike could target those forces and render many or all of them combat ineffective. Such a loss
could significantly limit the Marines’ role in an Indo-Pacific conflict, not only in terms of
firepower but also reconnaissance capabilities for the Joint Force.
Potential Impact of the Ukrainian Conflict on U.S. Ground Forces
in the Indo-Pacific Region
Russia’s February 2022 invasion of Ukraine has arguably changed the global security
environment. While some observers have said that U.S. and NATO deterrence failed in Ukraine,
others have suggested that such deterrence was both a “triumph and a failure”; for although the
United States and NATO failed to deter the attack, the conflict so far has been confined to
Ukraine, and nuclear weapons have not been used.165 In any case, given recent events in Ukraine,

160 Ibid.
161 Ibid., p. 104.
162 Ibid., p. 105.
163 Ibid.
164 Ibid., pp. 105-106.
165 Benjamin Jensen, “The Two Sides of Deterrence in Ukraine,” Center for Strategic and International Studies, March
30, 2022.
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policymakers may question the role and effectiveness of deterrence in the Indo-Pacific region
along with the future force posture and composition of U.S. ground forces in the region. In terms
of overall U.S. national security priorities, some experts have suggested replacing the current
Pacific-focused strategy with a “pivot to Europe”;166 while events in Ukraine have reportedly
resulted only in minor to the new China-focused National Defense Strategy.167 No matter where
strategic emphasis is placed, there are potential implications for U.S. ground forces in the Indo-
Pacific.
Some observers have suggested that U.S. and NATO force posture in Europe will likely change in
composition, numbers, and permanence. Examples of suggested changes include
 permanently stationing a Patriot unit in Poland, and
 permanently stationing at least three more brigade-equivalent Army combat units
in Poland, Germany, and Romania.168
In addition to these two examples, other types of U.S. ground forces could be committed to
Europe on both a permanent and rotational basis. Should this occur, new units allocated to Europe
might not be available for the Indo-Pacific, which, in the case of high–demand, low-density units
such as Patriot and THAAD, could pose serious operational consequences. If more U.S. ground
forces are allocated to Europe, Congress might decide to examine how this change would affect
U.S. ground force posture in the Indo-Pacific and the ability for the Army and Marines to fulfil
their operational roles.
Another implication is funding. Army and Marine funding could be influenced by a shift in
priority from the Indo-Pacific to Europe and NATO. The U.S. response to Russia’s attack of
Ukraine was unforeseen and remains fluid. As a result, the resource implications are undefined
beyond contingency funds provided to support current operations. In the longer term, Ukraine and
NATO-related funding requirements could be part of the Future Years Defense Program
(FYDP).169
Unless future defense budgets increase to account for these requirements, it is possible that
funding for Army and Marine efforts in the Indo-Pacific might decrease to fund European-related
initiatives. Of particular concern for some are ongoing Army and Marine Corps long-range
precision fires efforts, which are central to Indo-Pacific deterrence and warfighting missions. In
addition, support of vital Navy programs, such as the LAW and NSM, and funding for the PDI,
which the Army and Marines also depend upon, might be influenced by current and future
European security resource requirements. In its oversight and authorization and appropriations
roles, Congress may play a critical role in arbitrating emerging European security requirements
with ongoing and future Indo-Pacific requirements.

166 P. Michael McKinley, “It’s Time to Pivot Back to Europe,” Politico Magazine, February 24, 2022.
167 Jack Detsch, “Pentagon Rolls Out Defense Strategy Amid War in Europe,” Foreign Policy, March 28, 2022.
168 The Scowcroft Center Task Force on Deterrence and Force Posture, “Defending Every Inch of NATO Territory:
Force Posture Options for Strengthening Deterrence in Europe,” Atlantic Council, March 9, 2022.
169 The Future Years Defense Program (FYDP) (10 U.S.C. §221) summarizes forces, resources, and equipment
associated with all DOD programs. The FYDP displays total DOD resources and force structure information for five
years: the current budgeted year and four additional years. See https://acqnotes.com/acqnote/acquisitions/future-year-
defense-program-fydp, accessed April 1, 2022.
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U.S. Ground Forces in the Indo-Pacific: Background and Issues for Congress

Author Information

Andrew Feickert

Specialist in Military Ground Forces

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