The 2019-2020 Iran Crisis and U.S. Military Deployments

The 2019-2020 Iran Crisis and U.S. Military Deployments

January 9, 2020
The 2019-2020 Iran Crisis and U.S. Military Deployments
The January 2, 2020, U.S. drone strike against Iranian
Recent Deployments
Major General Qasem Soleimani, the subsequent Iranian
Precise figures of deployed U.S. personnel are difficult to
counter-strike on bases hosting U.S. personnel in Iraq, and
determine due to unit rotations in and out of a given theater.
recent deployments of U.S. military forces to the Middle
According to DOD, as of June 19, 2019, “there are
East have prompted widespread concerns about whether the
approximately 60-80,000 U.S. troops in the U.S. Central
United States is preparing to engage in another major
Command area of responsibility,” including approximately
military campaign in the region. Yet at present, the flow of
13,000 troops in Afghanistan and 5,200 in Iraq. In recent
additional forces into the U.S. Central Command
months, the Pentagon has announced several troop and
(CENTCOM) area of responsibility (AOR) suggests that
capability movements to and from the CENTCOM theater;
the Department of Defense (DOD) is posturing itself in the
with rotations, these announced deployments total
region defensively, with the ability to respond to
approximately 10,000 additional troops. Key
aggression, if necessary. The design of this posture may be
announcements, which should be treated as illustrative
altered should there be changes to security or political
rather than definitive deployment figures, include the
conditions on the ground, or political objectives for the
following:
region.
 On May 5, 2019, then-National Security Adviser
Figure 1. The CENTCOM AOR
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

Created by CRS. Presence data from CENTCOM.mil (2016); DOD
sent earlier to operate Patriot missile defense
Base Structure Report (2015); several federal contracting
equipment, and sending additional combat and
announcements (https://govtribe.com, 2015); MilitaryBases.com
reconnaissance aircraft.
(2016); and CRS analysis. Map boundaries from data from Dept. of
 On June 17, 2019, then-Acting Defense Secretary
State (2015); Esri (2014). Names and boundary representations are
Patrick Shanahan announced that the United States
not necessarily authoritative. Date of map: January 8, 2020.
was sending an additional 1,000 military personnel
to the Gulf “for defensive purposes.”
Force Employment Goals?


The Trump Administration has stated that its “core
On July 18, 2019, U.S. defense officials said that an
objective … is the systemic change in the Islamic
additional 500 U.S. troops would deploy to Saudi
Republic’s hostile and destabilizing actions, including
Arabia. The deployment, to Prince Sultan Air Base
blocking all paths to a nuclear weapon and exporting
south of Riyadh, reportedly will include fighter
terrorism.” Most recently, U.S. officials have argued that
aircraft and air defense equipment.
additional forces flowing in the region, as well as the strike
 On September 20, 2019, U.S. officials announced a
against Soleimani, are intended to “re-establish deterrence.”
“moderate” (widely interpreted as 200 personnel)
deployment of additional U.S. forces to Saudi
The military is but one tool of national power that could be
Arabia and the UAE. The forces reportedly
used in a variety of ways to achieve the above stated U.S.
accompany additional missile defense systems and
objectives. These range from increasing presence and
combat aircraft sent to facilities in those countries,
posture in the region to seeking regime change. As with any
use of the military instrument, any choice to employ U.S.
and are “defensive in nature.”
forces—or not—is an inherently risky endeavor and could
 On October 11, 2019, U.S. officials announced the
result in retaliatory Iranian action and/or the further
deployment of additional forces and capabilities to
escalation of a crisis in unpredictable ways. Iran’s actions
Saudi Arabia, including approximately 1,800 air
may influence U.S. force levels as much as or more so than
U.S. plans.
https://crsreports.congress.gov

The 2019-2020 Iran Crisis and U.S. Military Deployments
defense personnel, fighter squadrons, and an air
What Might Be the Impact on Regional and Global
expeditionary wing.
Basing and Posture?

U.S. expeditionary operations are enabled by a network of
In response to attacks on the U.S. embassy in
American bases and facilities hosted in allied and partner
Baghdad, on December 31, 2019, DOD announced
countries. Basing U.S. troops on foreign soil is a sensitive
the deployment to Kuwait of an infantry battalion
matter for host countries because such U.S. force
from the Immediate Response Force (IRF) of the
deployments—which are generally subject to U.S. rather
82nd Airborne Division, with 750 soldiers to deploy
than host nation legal jurisdiction—are inherently in tension
immediately and additional forces from the IRF
with a host nation’s sovereignty. As a result, the political-
(about 3,000 military personnel) deploying
military relationships with the countries that host U.S.
thereafter. A small (likely platoon-size) element of
troops require careful negotiation and management. Recent
the 173rd Brigade is also reportedly deploying to the
events, to include the Soleimani strike and Iranian counter-
region, possibly to Lebanon.
strike, could complicate bilateral negotiations on U.S.

forward bases, both in Iraq as well as in other parts of the
On January 5, 2020, DOD officials announced that a
world. This may be particularly the case with regard to East
task force of U.S. Special Operations Forces,
Asia, which DOD officials have identified as their “priority
including Rangers, was deployed to the Middle East.
theater” because of a need to keep pace with China’s
 On January 6, 2020, DOD announced that the 26th
actions, and where discussions are already sensitive due to
Marine Expeditionary Unit was being directed to
U.S. concerns about burden-sharing issues.
the Mediterranean.

Is DOD Adequately Prepared for Hybrid and
On January 6, 2020, it was reported that DOD
Irregular Warfare?
would be sending six B-52 Stratofortress bombers
While the aftermath of the January 8, 2020, Iranian missile
to Diego Garcia in the Indian Ocean, to be
counterstrikes is still evolving, many practitioners and
available for operations in Iran, if ordered.
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
Kathleen J. McInnis, Specialist in International Security
the robustness of Dynamic Force Employment and whether
it sufficiently mitigates readiness and availability risks.
IF11403
https://crsreports.congress.gov

The 2019-2020 Iran Crisis and U.S. Military Deployments

Disclaimer
This document was prepared by the Congressional Research Service (CRS). CRS serves as nonpartisan shared staff to
congressional committees and Members of Congress. It operates solely at the behest of and under the direction of Congress.
Information in a CRS Report should not be relied upon for purposes other than public understanding of information that has
been provided by CRS to Members of Congress in connection with CRS’s institutional role. CRS Reports, as a work of the
United States Government, are not subject to copyright protection in the United States. Any CRS Report may be
reproduced and distributed in its entirety without permission from CRS. However, as a CRS Report may include
copyrighted images or material from a third party, you may need to obtain the permission of the copyright holder if you
wish to copy or otherwise use copyrighted material.

https://crsreports.congress.gov | IF11403 · VERSION 3 · NEW