INSIGHTi

Ukraine: New U.S. Deployments to Europe
Might Raise War Powers Resolution
Questions
March 15, 2022
In response to Russia’s invasion of Ukraine, and in coordination with NATO allies, President Biden has
announced the deployment of U.S. armed forces to Poland, Romania, Bulgaria, Lithuania, Estonia,
Latvia, Greece, and the Czech Republic, as well as Germany, to defend the eastern flank of NATO. These
deployments might raise questions about the role of Congress under the War Powers Resolution (WPR)
concerning the use of U.S. armed forces in connection with the Ukraine conflict.
Presidential Reporting of Deployments Under the War Powers Resolution
Congress enacted the WPR to create congressional-executive procedure, triggered by presidential
consultation with and notification to Congress, for decisions to use U.S. armed forces. Pursuant to Section
4, the President must notify the Speaker of the House and the President pro tempore of the Senate within
48 hours after introducing U.S. armed forces (1) into active or imminent hostilities, (2) into a foreign
nation while equipped for combat (except when solely for supply, repair, or training), or (3) in numbers
that “substantially enlarge” combat-equipped, foreign-deployed U.S. armed forces. The notification must
describe the “circumstances necessitating” the deployment, its “estimated scope and duration,” and the
“constitutional and legislative authority” for the decision. Notifications are usually made publicly
available, but they can be provided in partially or entirely classified form. The President is required to
“provide such other information as the Congress may request” in connection with a notification, and must
report to Congress on continuing deployment at least once every six months.
The Biden Administration has announced deployments of approximately 15,000 U.S. troops to and within
Europe in response to Russia’s invasion. The President has not made any publicly available notifications
pursuant to Section 4 regarding these deployments. While some of the new deployments have a supply or
training element, they might not be “solely” for that purpose, as they are intended for NATO defense.
Congress may consider whether these new deployments “substantially enlarge” existing deployments. For
examples, U.S. troop presence in Poland has reportedly increased from about 4,000 to 8,700 or more, and
U.S. deployment to Romania increased from about 900 to 1,900 or more. At least 7,000 additional U.S.
troops have deployed to Germany, and might have redeployed elsewhere in Europe. In addition, no
Congressional Research Service
https://crsreports.congress.gov
IN11890
CRS INSIGHT
Prepared for Members and
Committees of Congress

---

Congressional Research Service
2
Section 4 notifications from the President concerning initial U.S. deployments to most of NATO’s eastern
member states, some of which have hosted U.S. troops for several years, have been publicly reported.
Determining “Hostilities”
The WPR contains provisions circumscribing the President’s authority to introduce U.S. armed forces
into “hostilities.” While the executive branch often seeks to foreclose congressional findings of hostilities
for the purposes of the WPR, the resolution itself seems to seek the involvement of Congress in
determining whether active or imminent hostilities exist, to “insure that the collective judgment of both
the Congress and the President will apply.” Section 4’s notification requirements are not just for
hostilities, but for all combat-equipped deployments, creating a process that informs and involves
Congress in situations where interbranch disagreement and possible changes in circumstances might
require a decision on certain uses of U.S. armed forces based on such “collective judgment.”
The term “hostilities” is not directly defined in the WPR. According to executive branch interpretation,
the term applies only to active exchanges of fire between U.S. and enemy forces. The legislative history
of the WPR, however, states it also “encompasses a state of confrontation in which no shots have been
fired but where there is a clear and present danger of armed conflict,” and such hostilities are “imminent”
when “there is a clear potential either for such a state of confrontation or for actual armed conflict.” The
116th Congress agreed to two resolutions requiring removal of U.S. armed forces (both vetoed) utilizing
broadened concepts of hostilities regarding U.S. military involvement in Yemen and against Iran.
Regarding the current situation, the Biden Administration has maintained that U.S. armed forces will not
fight in Ukraine, but has also stated that recent deployments are intended for defense of NATO countries,
including the use of military force if Russia attacks a NATO ally.
Determining the President’s Authorities
Absent a Section 4 notification, it is not clear which constitutional and legislative authorities the President
is relying on for these new deployments, or whether this reliance comports with the provisions of the
WPR. The Administration has confirmed that no current legislation authorizes military action against
Russia. The President’s exclusive constitutional powers to introduce U.S. armed forces into hostilities,
according to the WPR, are limited to defense of the United States and its armed forces against armed
attack. While the North Atlantic Treaty commits NATO member states to assist a member when attacked,
it does not require use of military force, stating instead that a member state may take “such action as it
deems necessary.” Additionally, the WPR states that treaties cannot serve as domestic authority for
introducing U.S. armed forces into hostilities. The executive branch has taken the position that the
President can direct extensive military operations if they do not constitute “war” in the constitutional
sense and such operations serve a sufficient national interest.
Possible Employment of WPR Procedure
Some Members of Congress have addressed the issue of the shared constitutional war powers of Congress
and the President, calling on the President to consult with Congress and seek specific legislative
authorization for any use of military force related to Russia’s invasion of Ukraine, in accordance with the
WPR. Arguably the absence of Section 4 notifications concerning Ukraine-related deployments might
serve to short-circuit the process of shared decisionmaking intended by the WPR. Some Members of
Congress might wish to request that the President provide Section 4 notifications that explain not only the
practical and policy decisions to use U.S. armed forces in response to Russia’s invasion of Ukraine, but
also the asserted authorities that permit such use.

---

Congressional Research Service
3
Author Information

Matthew C. Weed

Specialist in Foreign Policy Legislation




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.

IN11890 · VERSION 1 · NEW

---