January 9, 2020
The 2019-2020 Iran Crisis and U.S. Military Deployments
The January 2, 2020, U.S. drone strike against Iranian
forces—or not—is an inherently risky endeavor and could
Major General Qasem Soleimani, the subsequent Iranian
result in retaliatory Iranian action and/or the further
counter-strike on bases hosting U.S. personnel in Iraq, and
escalation of a crisis in unpredictable ways. Iran’s actions
recent deployments of U.S. military forces to the Middle
may influence U.S. force levels as much as or more so than
East have prompted widespread concerns about whether the
U.S. plans.
United States is preparing to engage in another major
military campaign in the region. Yet at present, the flow of
Recent Deployments
additional forces into the U.S. Central Command
Precise figures of deployed U.S. personnel are difficult to
(CENTCOM) area of responsibility (AOR) suggests that
determine due to unit rotations in and out of a given theater.
the Department of Defense (DOD) is posturing itself in the
According to DOD, as of June 19, 2019, “there are
region defensively, with the ability to respond to
approximately 60-80,000 U.S. troops in the U.S. Central
aggression, if necessary. The design of this posture may be
Command area of responsibility,” including approximately
altered should there be changes to security or political
13,000 troops in Afghanistan and 5,200 in Iraq. In recent
conditions on the ground, or political objectives for the
months, the Pentagon has announced several troop and
region.
capability movements to and from the CENTCOM theater;
with rotations, these announced deployments total
Figure 1. The CENTCOM AOR
approximately 10,000 additional troops. Key
announcements, which should be treated as illustrative
rather than definitive deployment figures, include the
following:
On May 5, 2019, then-National Security Adviser John Bolton
announced that the United States was accelerating the
previously planned deployment of the USS Abraham Lincoln
Carrier Strike Group in response to tensions to the region and
sending a bomber task force to the Persian Gulf area. The
Lincoln was relieved by the USS Harry S. Truman Carrier Strike
Group in December 2019.
On May 24, 2019, DOD said that the President approved a
plan to augment U.S. defense and deterrence against Iran by
deploying to the Gulf region an additional 900 military
personnel, extending the deployment of another 600 that were
sent earlier to operate Patriot missile defense equipment, and
sending additional combat and reconnaissance aircraft.
Map: CRS, Jan. 8, 2020. Presence data: CENTCOM.mil (2016); DOD
Base Structure Report (2015); federal contracting announcements
On June 17, 2019, then-Acting Defense Secretary Patrick
Shanahan announced that the United States was sending an
(https://govtribe.com, 2015); MilitaryBases.com (2016); and CRS
additional 1,000 military personnel to the Gulf “for defensive
analysis. Map boundaries: Dept. of State (2015); Esri (2014). Names
purposes.”
and boundaries not necessarily authoritative.
On July 18, 2019, U.S. defense officials said that an additional
500 U.S. troops would deploy to Saudi Arabia. The
Force Employment Goals?
deployment, to Prince Sultan Air Base south of Riyadh,
The Trump Administration has stated that its “core
reportedly wil include fighter aircraft and air defense
objective … is the systemic change in the Islamic
equipment.
Republic’s hostile and destabilizing actions, including
On September 20, 2019, U.S. officials announced a
blocking all paths to a nuclear weapon and exporting
“moderate” (widely interpreted as 200 personnel) deployment
terrorism.” Most recently, U.S. officials have argued that
of additional U.S. forces to Saudi Arabia and the UAE. The
additional forces flowing in the region, as well as the strike
forces reportedly accompany additional missile defense
against Soleimani, are intended to “re-establish deterrence.”
systems and combat aircraft sent to facilities in those countries,
and are “defensive in nature.”
The military is but one tool of national power that could be
On October 11, 2019, U.S. officials announced the
used in a variety of ways to achieve the above stated U.S.
deployment of additional forces and capabilities to Saudi
objectives. These range from increasing presence and
Arabia, including approximately 1,800 air defense personnel,
posture in the region to seeking regime change. As with any
fighter squadrons, and an air expeditionary wing.
use of the military instrument, any choice to employ U.S.
www.crs.gov | 7-5700
The 2019-2020 Iran Crisis and U.S. Military Deployments
In response to attacks on the U.S. embassy in Baghdad,
than host nation legal jurisdiction—are inherently in tension
on December 31, 2019, DOD announced the deployment
with a host nation’s sovereignty. As a result, the political-
to Kuwait of an infantry battalion from the Immediate
military relationships with the countries that host U.S.
Response Force (IRF) of the 82nd Airborne Division, with 750
troops require careful negotiation and management. Recent
soldiers to deploy immediately and additional forces from the
events, to include the Soleimani strike and Iranian counter-
IRF (about 3,000 military personnel) deploying thereafter. A
strike, could complicate bilateral negotiations on U.S.
small (likely platoon-size) element of the 173rd Brigade is also
forward bases, both in Iraq as well as in other parts of the
reportedly deploying to the region, possibly to Lebanon.
world. This may be particularly the case with regard to East
On January 5, 2020, DOD officials announced that a task
Asia, which DOD officials have identified as their “priority
force of U.S. Special Operations Forces, including Rangers, was
theater” because of a need to keep pace with China’s
deployed to the Middle East.
actions, and where discussions are already sensitive due to
U.S. concerns about burden-sharing issues.
On January 6, 2020, DOD announced that the 26th Marine
Expeditionary Unit was being directed to the Mediterranean.
Is DOD Adequately Prepared for Hybrid and
On January 6, 2020, it was reported that DOD would be
Irregular Warfare?
sending six B-52 Stratofortress bombers to Diego Garcia in the
While the aftermath of the January 8, 2020, Iranian missile
Indian Ocean, to be available for operations in Iran, if ordered.
counterstrikes is still evolving, many practitioners and
experts note that the United States has heretofore primarily
In the fall of 2019, the Trump Administration also
been engaged in a hybrid, irregular conflict with Iran for
assembled what it calls the International Maritime Security
decades, with the exception of U.S.-Iran naval clashes
Construct, a coalition that monitors Iranian threats and
during the 1980-1988 Iran-Iraq War. Hybrid and irregular
could use military assets to protect commercial shipping in
warfare are commonly understood to be instances when
the Gulf. As of November 2019, the IMSC’s contributors
belligerents, to varying extents, collaborate with proxies
included the United States, United Kingdom, Australia,
(including, but not limited to, militias, other countries,
Kingdom of Saudi Arabia, Albania, United Arab Emirates,
criminal networks, corporations and hackers) and
and Bahrain.
deliberately sow confusion as to what constitutes “civilian”
versus “military” activities in order to create plausible
Questions for Congress
deniability for a given action. Many observers expect that
These deployments raise a number of potential issues for
the U.S.-Iranian relationship will return to a state of mostly
Congress in its oversight and authorization capacities.
irregular/hybrid warfare. However, given the Trump
These include the following:
Administration’s overall strategic guidance to prioritize
great power competition and lethality, some are concerned
What Might Be the Impact on Readiness and
that insufficient attention and resources are being dedicated
Availability of U.S. Forces for Other Missions?
toward preparing U.S. forces to wage irregular/hybrid
warfare.
Ultimately, any troops that are deployed to the CENTCOM
AOR, as well as those training to replace them, will be
Do Recent Deployments Align with National
taken out of the “pool” of forces available and ready to
Strategy?
respond to other possible contingencies. DOD forces are a
finite resource; the deployment of assets to the CENTCOM
According to its strategy documents, in the Trump
AOR will necessarily affect the availability of forces for
Administration’s view, effectively competing—
other theaters and contingencies. While the additional
economically, diplomatically, and militarily—with China
commitment of U.S. troops since this June has thus far been
and Russia is the key national security challenge facing the
relatively modest, ongoing operations in Afghanistan
United States today. As Iran reportedly is a lesser priority
(Resolute Support), Central and Eastern Europe (Operation
relative to these other challenges, some observers contend
Atlantic Resolve), and the unpredictable threat from North
that a shift in U.S. resources away from the CENTCOM
Korea could create a demand for additional U.S. forces that
AOR and toward Europe and Asia is therefore necessary.
is not currently forecasted.
Viewed in this light, recent deployments of forces and
resources to the Middle East may create tension with the
DOD officials generally contend that force planning
overall strategic goals of this Administration. However
concepts, like Dynamic Force Employment, enable DOD to
other observers, including the National Defense Strategy
shift key U.S. military assets rapidly from one theater to
Commission, questioned whether this redirection of assets
another and can mitigate some of the risk associated with
away from the Middle East was ever feasible.
diverting resources towards CENTCOM. Others question
the robustness of Dynamic Force Employment and whether
Kathleen J. McInnis, kmcinnis@crs.loc.gov, 7-1416
it sufficiently mitigates readiness and availability risks.
IF11403
What Might Be the Impact on Regional and Global
Basing and Posture?
U.S. expeditionary operations are enabled by a network of
American bases and facilities hosted in allied and partner
countries. Basing U.S. troops on foreign soil is a sensitive
matter for host countries because such U.S. force
deployments—which are generally subject to U.S. rather
www.crs.gov | IF11403 · VERSION 4 · NEW