War Powers Issues: U.S. Use of Military Force Against Iran

War Powers Issues: U.S. Use of Military Force Against Iran

War Powers Issues: U.S. Use of Military Force Against Iran

June 23, 2025 (IN12577)

The War Powers Resolution (WPR), among other things, requires the President to inform Congress of certain deployments abroad and the "introduction of United States Armed Forces into hostilities," providing expedited procedures for congressional consideration of authorization or disapproval of such presidential action. In connection with the intensified Israel-Iran conflict, U.S. air and naval forces at President Trump's direction struck Iranian nuclear facilities on June 21. Some Members of Congress have questioned the President's authority to use military force against Iran, asserted Congress's constitutional role in such decisions, and criticized the President's decision to act without seeking authorization from Congress. Some Members have stated the President possesses constitutional authority for such action and supported the President's decision.

The President had previously ordered additional forces to the Middle East in response to the conflict, and U.S. forces in Israel and international waters have reportedly defended Israel by intercepting Iranian missiles. U.S. forces in the region are based and otherwise deployed within range of Iranian military strike capabilities, and have been targeted in at least one Iranian military response to date, though no casualties were reported.

Presidential Reporting Under the War Powers Resolution

The WPR requires presidential consultation with and notification to Congress concerning 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 U.S. forces "are introduced" into active or imminent hostilities, or otherwise into a foreign nation while equipped for combat. The notification must describe the "circumstances necessitating" the introduction, the "estimated scope and duration of the hostilities or involvement," and the "constitutional and legislative authority" for the decision. The President is required to "provide such other information as the Congress may request" in connection with a notification.

On June 23, President Trump submitted a WPR notification explaining the June 21 Iran strikes, asserting constitutional authority for the action based on his role "as Commander in Chief and Chief Executive and pursuant to [his] constitutional authority to conduct United States foreign relations." He did not cite any statutory authority. He noted the possibility of further uses of military force "to address further threats or attacks."

Previous WPR notifications on multiple occasions since 2019 have described U.S. use of military force against Iranian forces and U.S. operations to defend against Iranian military threats and actions. Other U.S. and Iranian actions have been reported but not included in publicly available WPR notifications.

"Hostilities" Under the WPR

The WPR contains provisions circumscribing the President's authority to introduce U.S. Armed Forces into "hostilities." While the executive branch might attempt to foreclose congressional findings of hostilities, the WPR seems to seek the involvement of Congress to "insure that the collective judgment of both the Congress and the President will apply."

The term "hostilities" is not defined in the WPR. According to an executive branch interpretation, the term applies only to active exchanges of fire between U.S. and "opposing units of hostile forces," and U.S. use of military force does not amount to "hostilities" under the WPR if military force is "limited in nature, scope, and duration," based on various factors. The House report accompanying the WPR, in contrast, states that the term includes not only the use of military force by and against U.S. Armed Forces but 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." Such hostilities are "imminent" when "there is a clear potential either for such a state of confrontation or for actual armed conflict."

In the current situation concerning Iran, determining "hostilities" might depend on interpretation of the term as well as the breadth of information considered. If hostilities exist only during active exchanges of fire, it could be argued that hostilities would end as soon as an exchange of fire ceases, which may have already occurred. It could also be argued that hostilities have existed during the overall period when uses of force have occurred intermittently in the context of an ongoing state of confrontation between U.S. and Iranian forces, possibly extending back several years and continuing at present.

Presidential Authority to Conduct Hostilities

The President has stated that he has the authority to direct the use of military force against Iran. This assertion seems to align with previous executive-branch interpretation asserting Article II authority to use military force in the national interest and when such action would not "rise to the level of a war in the constitutional sense." According to the WPR, the President's exclusive constitutional powers to introduce U.S. Armed Forces into hostilities are limited to defense of the United States or its Armed Forces against an armed attack creating a "national emergency"; continuing hostilities must receive congressional authorization.

Further attacks by Iran, if they were to occur, might prompt defensive U.S. military action including further use of military force. The WPR seems to require the President to submit to Congress for approval or disapproval any deployments of U.S. Armed Forces resulting in hostilities, whether such hostilities are offensive or defensive in nature.

Possible Congressional Employment of WPR Measures

Congress may choose to authorize or terminate the use of Armed Forces with regard to any hostilities involving Iran; the WPR requires presidential consultation and reporting to inform that choice. The WPR empowers Congress to consider legislative war powers measures whether or not the President engages in the process. Congress may request information from the Administration that directly addresses war powers authorities.

If Congress were to find that U.S. forces are engaged in ongoing unauthorized hostilities with Iranian forces, the WPR and related legislation provide expedited procedures to consider authorizing, or requiring immediate removal of U.S. forces from, such hostilities. Privileged measures have been introduced in both Chambers to require the removal of U.S. forces from hostilities with Iran. If Congress does not adopt either measure within 60 days, the President must terminate the use of U.S. forces related to any required notification without further congressional action, subject to a 30-day extension if necessary for orderly removal of forces. According to the WPR's provisions, this 60-day period is not a grant of authority to conduct hostilities, but instead serves as a window for Congress to decide whether to cure the unauthorized use of the military.