Part III: Use of Force

The constitution divides war powers between the executive and legislative branches, granting Congress the authority to declare war and provide support for U.S. armed forces under Article I.¹ Article II specifies that the president is commander in chief of U.S. armed forces.² However, what these powers mean for the use of force are not entirely clear: the Congressional Research Service notes that “there as long been controversy over whether [the president] is constitutionally authorized to send forces into hostile situations abroad without a declaration of war or other congressional authorization.”³

Since 1973, when it was enacted over President Richard Nixon’s veto, the WPR has been the primary mechanism that Congress has to enforce transparency on the executive with regards to the use of force and “assert its own constitutional role.”⁴

The WPR has several requirements related to the use of force:

Section 4(a). Section 4(a) of the WPR enumerates reporting requirements to Congress. These requirements are the WPR’s “core means of providing transparency and ensuring Congress has the necessary information to make decisions regarding how the nation’s armed forces are used abroad.”⁵ It requires the president to notify Congress whenever U.S. armed forces are introduced “(1) into hostilities or into situations where imminent involvement in hostilities is clearly indicated by the circumstances; (2) into the territory, airspace or waters of a foreign nation, while equipped for combat,” with a few limited exceptions; “or (3) in numbers which substantially enlarge United States Armed Forces equipped for combat already located in a foreign nation.” This reporting must be provided within 48 hours of the triggering event in the absence of a declaration of war.

Section 5(b) and (c). The president’s submission of this reporting triggers a 60-day clock, which can be extended to 90 days under certain circumstances. At the end of this period, the president must cease the use of these U.S. armed forces unless Congress votes to authorize a continued engagement.⁶

In the 1980’s, Congress adopted separate provisions that allowed it to propose a joint resolution related to the removal of U.S. forces. This legislation is considered via expedited procedures.⁷

Section 3. Section 3 of the WPA requires that the president “in every possible instance… consult with Congress before introducing” U.S. forces into hostilities or imminent hostilities.”⁸ The meaning of consultation was left fairly general in the final version of the legislation, although the House report clarified that the House had considered and rejected the notion that “consultation should be synonymous with merely being informed. Rather, consultation in this provision means that a decision is pending on a problem and members of Congress are being asked by the President for their advice and opinions.”⁹

Congress has declared war 11 times in five conflicts; however, Congress has not formally declared war since June 4, 1942, when it declared war against Bulgaria, Hungary, and Romania. Instead, it has passed use-of-force statutes via joint resolutions that are typically “narrower in scope” than a declaration of war, according to the Constitution Project.¹⁰ The AUMF passed in 2001 and another AUMF passed in 2002 are the two most recent use-of-force resolutions.

2001 AUMF

The 2001 AUMF was passed in the week after September 11, 2001. It authorized the president to “use all necessary and appropriate force against those nations, organizations, or persons he determines planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001, or harbored such organizations or persons.”¹¹

Since its passage, the 2001 AUMF has become “the central statutory enactment related to the war on terrorism,”¹² as executive branch officials have interpreted this AUMF to authorize the use of force against al-Qaeda and the Taliban outside of Afghanistan— including ISIS, beginning in 2014, which the Obama administration argued counted as a “successor force” of al-Qaeda since al-Qaeda was a predecessor to ISIS—ISIS could not qualify as an “associated force” of al-Qaeda since they were fighting each other at the time.¹³ As of February 2018, administrations have invoked the 2001 AUMF to justify 41 operations in 19 countries, according to the Congressional Research Service. Administrations also often cite the 2001 AUMF in conjunction with other legal justifications, further obscuring which authorities are covered by the 2001 AUMF.¹⁴

Critics have argued that because the 2001 AUMF has been interpreted so broadly and has no sunset clause, it has effectively served as a blank check for war.¹⁵ Advocates concerned that the United States has been involved in forever wars since 2001 see the 2001 AUMF as these wars’ central domestic legal component. Other critics have called for the AUMF to be repealed and replaced rather than just repealed, arguing that the AUMF “is outdated and fails to provide appropriate legal authorization or characterize the threats to American national security with adequate precision.”¹⁶

2002 AUMF

The 2002 AUMF authorizes the president to use force in order to “(1) defend the national security of the United States against the continuing threat posed by Iraq; and (2) enforce all relevant United Nations Security Council resolutions regarding Iraq.”¹⁷

The 2002 AUMF was originally intended to authorize the 2003 U.S. invasion of Iraq. However, both the Obama and Trump administrations have since cited the 2002 AUMF as a reinforcing authority for operations conducted against ISIS, usually in tandem with the 2001 AUMF.¹⁸ At the same time, the Obama administration said that it supported the repeal of 2002 AUMF “since it is no longer used for any U.S. government activities.”¹⁹

1.Recommendation: Invoke the War Powers Resolution in legislation

Congress can pass legislation with regards to specific conflict contexts invoking the WPR. It should be noted that the obstacles facing successful passage of such legislation are very high. It will be difficult for Congress to invoke the WPR with regards to a conflict that an administration claims is authorized by statute. However, such legislative efforts can still provide benefits in terms of exercising leverage on the executive branch—and on U.S. security partners, who often take Congress’s approval seriously—when invoked.

The WPR has faced a number of challenges since it was enacted in 1973, namely expansive interpretations by presidential administrations of existing authorizations for the use of force and narrow interpretations of key terms in the WPR, such as the term “hostilities.”²⁰ Presidents have introduced armed forces into hostilities without reporting to Congress, and Congress has been reluctant to push back by initiating procedures to enforce the WPR.²¹ The automatic withdrawal provision of section 5(b) has received some blame for this issue, since it has made presidents reluctant to formally report to Congress, thereby triggering the 60-day clock.²² The 60-day clock has also been “misconstrued to give the President a sixty-day ‘free pass’ to use force without congressional authorization and to allow congress to do nothing.”²³

Thus, even if Congress does not assert its authorities under the WPR in the broadest sense, there is still considerable room for Congress to exert oversight over the use of force in hostilities.

Congress passed legislation in 2018 and 2019 seeking to end U.S. support for the Saudi-led coalition’s intervention in Yemen (note that the legislation drew a distinction between the war against the Houthis and the counter-terrorism war in Yemen). While the president vetoed the legislation passed by both houses in 2019, this is a useful example of how Congress can constructively use the WPR to gain leverage over an administration in a particular conflict (see Appendix).

2. Recommendation: Demand WPR Reporting and Investigate Deployments of U.S. Forces Under Title 10

U.S. forces that are deployed under Title 10 training and assistance authorities could become engaged in hostilities even if their primary mission is to train and assist foreign militaries. Congress can demand reporting pursuant to the WPR on U.S. forces that are deployed under Title 10 and that may become engaged in hostilities. Congress, and specifically the House and Senate Armed Services Committees, can use their investigatory tools, including reporting requirements and holding hearings, to determine whether it has received complete and reliable information from the executive regarding Title 10 deployments.²⁴

In 2019, U.S. forces were deployed in at least 65 countries conducting counterterrorism-related training, according to the Costs of War Project.²⁵ Many of these deployments have the potential to become engaged in hostilities even if that is not their primary mission. In these cases, Congress is notified of a Title 10 deployment, but does not have a significant chance to offer input or authorize the use of force, even in situations where force may become necessary.

An incident in October 2017 in Niger, when four U.S. soldiers were killed and two more wounded in an ambush by a terrorist group affiliated with the Islamic State, aptly illustrates this problem. U.S. troops had been deployed to Niger since 2013 under Title 10, and the forces were on a reconnaissance patrol linked to U.S. counterterrorism operations in the Greater Sahel when they were ambushed.²⁶ While Trump administration officials initially asserted that U.S. forces were operating in Niger under Title 10 authorities, they reversed course in March 2018, arguing then that the 2001 AUMF applied to these forces at the time of the attack. In this case, Congress had been notified, consistent with the WPR, that U.S. troops that were equipped for combat in Niger. ²⁷

3. Recommendation: Repeal (and possibly replace) the 2001 and 2002 AUMFs

Repeal and Replace. Critics, including many members of Congress, have argued that the 2001 AUMF has been stretched well beyond its original intent. In a 2017 hearing, ranking member of the HFAC representative Eliot Engel noted “I was here when we passed this measure nearly 16 years ago and I have to say that none of us envisioned we would still be relying on it nearly two decades later to fight an enemy that didn’t even exist when the Twin Towers came down. It’s essentially become a blank check.”²⁸

Some members of Congress have proposed repealing the 2001 and 2002 AUMFs and replacing them with an authorization for the use of force that specifies combatants, including the Islamic State.²⁹ However, replacement bills must be carefully written so that they are not in practice as expansive as the existing AUMFs. For instance, a 2018 bill introduced by Sens. Bob Corker (R-Tenn.) and Tim Kaine (D-Va.) intended to “reaffirm the domestic legal basis” for ongoing conflicts against the Taliban and al-Qaeda while reasserting Congress’s role in use of force.³⁰ However, critics of this legislation have argued that the replacement actually grants the executive broader authority rather than reasserting Congress’s role in authorizing and conducting oversight of the use of force.³¹ Specifically, analysts worried that because the bill required Congress to affirmatively vote to remove a new set of associated forces added by the president, as the bill allowed—and that the affirmative vote would then be subject to a presidential veto—it actually passed additional responsibility to the executive to decide whether and how to expand the scope of the AUMF.

A replacement AUMF should also include sunset provisions limiting the expansion of the authorization over time, and/or requirements that the Authorization must be periodically affirmatively voted on by Congress in order to remain in force.³² Additionally, a replacement should be more specific about who is targeted, prohibit the targeting of “associated forces” without explicit Congressional approval, and specify which country or countries force where force is permitted to be used.

4. Recommendation: Defund and Conduct Oversight of the AUMFs

Even if Congress is not able to repeal the AUMFs, it can defund execution of the AUMFs and conduct oversight.

Defund. In addition to passing the AUMFs themselves, Congress has the discretion to appropriate funding for the AUMFs. Congress has provided much of the past annual funding for operations in Afghanistan and Iraq through the use of emergency supplemental bills, namely the Overseas Contingency Operations (OCO) fund, which is operated jointly by the DoD and State Department on top of their annually appropriated base budgets.³³

For example, in the past Congress has added amendments to appropriations legislation to prohibit the use of funds appropriated to DoD pursuant to the AUMFs, although these amendments have always been defeated.³⁴

Continued Oversight. Congress can also conduct continued oversight of the use of force. According to the Constitution Project, authorization does not mean the end of Congress’s duties around the use of force: these duties “continue as long as the use of force continues. Congress should not only conduct continuing oversight of the strategic uses of force, but also collect the information necessary to decide on supplemental appropriations.”