Editors’ note: This article is the sixth installment in our Still at War Symposium, which can be accessed here.

Almost twenty years have passed since the United States invaded Iraq to topple Saddam Hussein. After the invasion, U.S. forces remained in Iraq for eight years before withdrawing in 2011, only to return in 2014 to fight a new terrorist threat from the Islamic State of Iraq and Syria (ISIS). Today’s counter-ISIS mission in Iraq (ongoing since 2014) rests on a strong international legal basis, relying on Iraqi consent along with the principle of self-defense and the support of the U.N. Security Council. But U.S. domestic authorization has grown tenuous, based (like so many other current U.S. conflicts) on stretched interpretations of the 2001 and 2002 Authorizations for Use of Military Force (AUMFs), the latter of which dates back to the 2003 Iraq War itself. Meanwhile, the legal basis for recent U.S. military actions against Iranian-backed groups in Iraq is questionable as a matter of domestic and international law. While policy imperatives to keep limited military forces in Iraq remain, it is crucial to reevaluate the legal basis and policy objectives for continuing U.S. military operations there.

How the Counter-ISIS Campaign in Iraq Began

In 2011, President Barack Obama announced the withdrawal of U.S. military forces from Iraq, fulfilling his campaign promise to end the Iraq War that began under the Bush administration in 2003. But just three years later, U.S. troops returned, responding to the rapid advances and widely publicized atrocities of ISIS. At the head of a coalition of allied nations known as the Combined Joint Task Force-Operation Inherent Resolve (CJTF-OIR), and in close support of Iraqi and local forces (including Kurdish forces), the United States played a pivotal role in liberating vast swathes of territory from ISIS, degrading its capabilities, and preventing it from continuing to commit gross violations of international humanitarian law against local populations.

By 2017, ISIS no longer held territory in Iraq, and the Iraqi Security Forces (ISF) supported by the CJTF had liberated ISIS’s last stronghold in the city of Mosul (Iraq’s second largest city and ISIS’s de facto capital in Iraq). U.S. support for these operations played a decisive role in achieving that victory, contributing to ISIS’s territorial defeat.

Since 2017, the United States has retained a limited military presence in Iraq, mostly to train, advise, and support local forces which continue to perform counterterrorism operations. While ISIS no longer holds territory, it repeatedly has demonstrated an ability to resurge, temporarily taking control of towns and villages, or carrying out successful attacks against the ISF. For the most part, Iraqi authorities continue to see the need for – and support – a limited, continued U.S. military presence. But some local actors, particularly Shi’ite militia groups (SMGs) supported by Iran, have long objected to any U.S. military presence in Iraq. As the ISIS threat recedes, these domestic groups increasingly have called for the United States to leave, or be expelled from, Iraq.

Current U.S. Involvement in Iraq

In part responding to the growing Iraqi calls for withdrawal, the U.S. formally ended its latest combat mission in Iraq in December 2021. The decision to withdraw U.S. combat troops from Iraq was announced by President Joe Biden in July 2021 following a series of strategic dialogues between the U.S. administration and the Iraqi government, headed by Prime Minister Mustafa al-Kadhimi. But while coalition combat missions may be over, 2,500 U.S. troops remain in the country, providing training, advice, and support to the ISF for counter-ISIS operations. That residual force continues to operate at the invitation of the Iraqi government (which remains supportive of a continued presence both to help prevent an ISIS resurgence, and to retain U.S. political and economic benefits).

On multiple occasions in the past year, U.S. Central Command (CENTCOM) has indicated that there are no plans to withdraw these non-combat soldiers anytime soon. In March 2022, then-CENTCOM commander Gen. Frank McKenzie noted that: “[a]s we look into the future, any force level adjustment in Iraq is going to be made as a result of consultations with the government of Iraq…we just finished a strategic dialogue a few months ago ― we believe that will continue.” But the U.S. goal remains to develop ISF capabilities and, ultimately, to leave. According to Gen. McKenzie, “[r]ight now…Iraqis [are] doing the fighting. We’re still helping them. Over time you’d like for them to take a larger share of all the enabling that we’re doing now.”

While the United States has largely succeeded in securing ISIS’s territorial defeat, the group has enjoyed a sustained resurgence in 2019 and early 2020. ISF efforts (closely supported by CJTF) arrested that resurgence in late 2020 and 2021, but incidents like the Jan. 20, 2022, ISIS prison break at Ghweran, Syria, and the Jan. 21, 2022, massacre of 11 Iraqi Army soldiers in Diyala, Iraq should serve as a warning against complacency. Meanwhile, many government and NGO observers express concerns that local conditions could increase the risk of the return of ISIS, or a successor organization. Syria’s al-Hol refugee camp, in particular, is filled with families of ISIS members living in miserable conditions who are ripe for terrorist recruitment. While local Iraqi forces now perform almost all stabilization and counterterrorism activities against ISIS in Iraq, U.S. intelligence, logistics, training, and equipping continue to play a crucial role in enabling local forces and preventing ISIS from regrouping.

Even as the threat from ISIS has receded, Iranian-backed SMG attacks on U.S. forces have continued at a steady pace. From 2019 onwards, certain Shi’ite militias have engaged in a sustained campaign of attacks on U.S. positions in Iraq (and in Syria). This campaign followed President Donald Trump’s May 2018 withdrawal from the Iran nuclear deal and was exacerbated by his Jan. 2020 decision to assassinate Iranian Islamic Revolutionary Guard Corp (IRGC) Qods Force Commander, Maj. Gen. Qasem Soleimani, along with Abu Mahdi al-Muhandis, a senior SMG leader and the operational commander of Iraq’s Popular Mobilization Forces (PMF), a part of Iraq’s state armed forces. These SMGs are often affiliates of U.S. designated terrorist organizations such as Kata’ib Hezbollah, Asa’ib Ahl al-Haq, and Harakat al-Nujaba, but are also in many cases members of the PMF, formally part of the Iraqi military and within its chain of command (though in practice independent from it and uncontrolled) – presenting challenges for both Iraqi law enforcement and coalition forces seeking to prevent attacks and control illegal activity. Milita attacks have involved hundreds of rocket and suicide drone strikes against U.S. and coalition personnel, killing at least five U.S. citizens (in addition to one British citizen). In response, the United States has launched a series of strikes against SMGs in both Iraq and Syria, raising the troubling possibility that the United States will slide into a new, unauthorized conflict.

The Legal Basis for U.S. Operations in Iraq

Against this backdrop, questions as to the legality of continuing U.S. operations in Iraq are particularly salient. While operations against ISIS in Iraq retain a strong legal basis in both international and Iraqi domestic law, these bases do not extend to a conflict between the United States, Iran, and its proxies. And, despite the war on ISIS’s strong international legal footing in Iraq, U.S. domestic law justifications are weak at best, relying on stretched interpretations of the 2001 and 2002 Authorizations for Use of Military Force (AUMFs) and of the president’s authority under Art. II of the Constitution.

Counter-ISIS Operations

International Law. Compared with the 2003 invasion, U.S. operations in Iraq against ISIS have a strong basis in international law. From the outset of the counter-ISIS campaign in the summer of 2014, Iraqi government consent has been the legal cornerstone of U.S. and coalition operations in Iraq. U.N. Security Council backing, under UNSC resolutions like UNSCR 2249 of 2015, which called on states to “take all necessary measures” to prevent and suppress terrorist acts committed by ISIS, put CJTF-OIR on even stronger footing.

Consent is not always so straightforward as in the present case. Thus, it is worth briefly reviewing what makes a lawful claim of consent to use force within another state’s territory before exploring U.S. military action in Iraq. To permit another state’s intervention, the receiving state must give valid consent (meaning, inter alia, that the consent must be freely given and actually expressed) and the official or organ granting consent must have legitimate authority to do so (some debate exists as to what constitutes a legitimate authority, particularly in the context of weak governments and territory-controlling but unrecognized governments). Consent may also be limited, in terms of the objectives, means, or location. A state using armed force on the basis of another’s consent must operate within constraints imposed by the host state; failure to do so is a violation of international law. And similarly, should a host state withdraw its consent the operating state must withdraw its forces, or commit a jus ad bellum violation.

In Sept. 2014, when the United States launched its full-scale counter-ISIS campaign, U.S. land and air operations on Iraqi soil were being conducted at the invitation of the Iraqi government. Iraqi and U.S. government officials, scrambling to halt ISIS’s encroachment on Baghdad, had worked for months to lay the formal groundwork for this consent in closed door negotiations and in public statements. On June 25, 2014, Hoshyar Zebari (then-Minister for Foreign Affairs of the Republic of Iraq) transmitted a letter to the U.N. Secretary General and UNSC, noting that:

[w]e have previously requested the assistance of the international community. While we are grateful for what has been done to date, it has not been enough. We therefore call on the United Nations and the international community to recognize the serious threat our country and the international order are facing… …we need your support in order to defeat ISIL and protect our territory and people. In particular, we call on Member States to assist us by providing military training, advanced technology and the weapons required to respond to the situation, with a view to denying terrorists staging areas and safe havens.

Then, on Sept. 20, 2014, Ibrahim al-Ushayqir al-Ja‘fari (the new Iraqi foreign minister, Hoshyar and other Kurds having withdrawn from the Iraqi government in protest of Nouri al-Maliki’s rule) transmitted another letter to the United Nations. This time, Iraq noted its gratitude “for the military assistance it is receiving, including the assistance provided by the United States of America in response to Iraq’s specific requests.” The letter went on:

Iraq and the United States have entered into a Strategic Framework Agreement, and that Agreement will help to make such assistance more effective and enable us to make great advances in our war against ISIL. Although Iraq is in great need of the assistance of its friends in combatting this evil terrorism, it nonetheless attaches great importance to preserving its sovereignty and its ability to take decisions independently, both of which must be honoured in all circumstances.

The letter then confirmed that Iraq, “in accordance with international law and the relevant bilateral and multilateral agreements, and with due regard for complete national sovereignty and the [Iraqi] Constitution, [had] requested the United States of America to lead international efforts to strike ISIL sites and military strongholds, with [Iraq’s] express consent.”

These letters, along with other statements and agreements, are unambiguous (and undisputed) expressions of Iraqi consent for the United States to use force on the territory of Iraq against ISIS. In short, U.S. operations in Iraq are lawful as a matter of jus ad bellum since Iraq’s sovereign authority (the government of Iraq acting through the Council of Ministers), relying on powers permitted to it under Iraqi law, invited the United States to operate on Iraqi soil.

Iraqi consent, however, has subsequently been tested. The Jan. 3, 2020 killing of Soleimani andal-Muhandis in a U.S. drone strike at the perimeter of Baghdad airport most likely violated the written terms of Iraq’s consent. Not only were none of the targets affiliated with ISIS, but several of the dead (al-Muhandis included) were – as a matter of Iraqi law – members of the Iraqi armed forces by virtue of their positions in the PMF (incorporated by law into the ISF in 2016). The strike, authorized by President Trump in response to “an escalating series of attacks” on U.S. interests in Iraq, including on the U.S. Embassy, was immediately condemned across the Iraqi political spectrum (and internationally).

On Jan. 5, 2020, two days after the strike, members of Iraq’s parliament passed a non-binding resolution calling on the government to end all foreign troop presence in Iraq. The vote was boycotted by many Sunni and Kurdish representatives, and ultimately only 168 out of 329 representatives (3 more than quorum) attended the vote. Unlike the passage of a law, parliamentary resolutions are non-binding on the government (and the government at that time was Adil Abdul-Mahdi’s lame-duck caretaker government, constitutionally unable to take significant decisions). Additionally, while Iraq’s constitution and laws provide parliament with the power to ratify treaties and international agreements, the law does not explicitly provide parliament with the power to cancel agreements. That power lies with the government (and to date the Iraqi government has neither canceled the Strategic Framework Agreement, nor withdrawn consent for U.S. forces to be present in Iraq). As a result the resolution – though deeply symbolic – had no immediate effect on U.S. forces.

While Iraq’s consent was not withdrawn in early 2020, domestic Iraqi calls for U.S. withdrawal or expulsion (particularly from Shi’ite groups) became a core political rallying cry. Iranian-backed Shi’ite militia groups ramped up rocket and drone attacks on U.S. personnel, equipment, and positions in Iraq – frequently justifying these attacks with demands for U.S. withdrawal (and often citing the non-binding parliamentary resolution as a sign that the United States had remained in Iraq as an illegal occupying force). In June 2020, the Trump and Kadhimi administrations held the first round of a new Iraqi and U.S “strategic dialogue” designed – in part – to address the future of the U.S. military presence in Iraq.

Subsequent rounds of the strategic dialogue included a meeting between President Trump and Prime Minister Kadhimi in August 2020, and meetings between the Biden and Kadhimi administrations in April and July 2021. In April 2021, the parties “confirmed that the mission of U.S. and Coalition forces [had] now transitioned to one focused on training and advisory tasks, thereby allowing for the redeployment of any remaining combat forces from Iraq, with the timing to be established in upcoming technical talks.” Then, following the July 2021 talks in Washington D.C., the two governments announced:

…that the [U.S.-Iraqi] security relationship will fully transition to a training, advising, assisting, and intelligence-sharing role, and that there will be no U.S. forces with a combat role in Iraq by December 31, 2021.  The United States intends to continue its support for the ISF, including the Peshmerga, to build their capacity to deal with future threats.

So long as consent from the Iraqi government continues, the U.S. justification for a continued military presence in Iraq remains on solid legal footing under both international law and Iraqi domestic law. But if the United States were to (again) exceed the bounds of Iraq’s consent, not only would those actions likely be unlawful under international law, they could also provoke the Iraqi government to withdraw consent for any future U.S. operations in Iraq or to trigger termination of the Strategic Framework Agreement.

U.S. Domestic Law., In contrast to the international legal basis for U.S. military operations against ISIS in Iraq, reliance on the outdated 2001 and 2002 AUMFs as the domestic legal basis for these operations is a stretch (which is true for several of the conflicts examined in this Just Security series)

In his initial Aug. 2014 notifications to Congress of deployments and airstrikes in Iraq under the reporting requirements of the War Powers Resolution, Obama cited his powers as Commander in Chief and Chief Executive under Art. II of the U.S. Constitution as authority to undertake such action. But in his subsequent Sept.2014 notifications to Congress, the president cited the 2001 and 2002 AUMFs as domestic legal authority, claiming to have directed military operations in Iraq “pursuant to [his] constitutional and statutory authority as Commander in Chief (including the authority to carry out Public Law 107-40 and Public Law 107-243).” As Tess Bridgeman and Brianna Rosen explained in their article on Syria in this series, the use of the 2001 AUMF as a source of authority to target a group other than al-Qaeda, the Taliban, or a so-called “associated force” of those groups was a novel stretching of that authorization. The argument relies on a prior affiliation between ISIS’s predecessor organization and al-Qaeda from around 2004 – a tenuous expansion of the authorization stretching well beyond Congress’s original intent.

Meanwhile, reliance on the 2002 AUMF was also highly questionable. The 2002 AUMF was enacted to authorize the Iraq War in 2003. The text of the law permitted the president “to use the Armed Forces of the United States as he determines to be necessary and appropriate 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” (Section 3(a)). Given U.S. operations against ISIS in 2014 were being expressly conducted at the invitation of Iraq, and using collective self-defense of Iraq as a justification, the use of an authorization designed for use of force against Iraq and the continuing threat posed by Iraq is a stretch, at best. A broad interpretation of Section 3(a)(2) could justify use of the authorization to justify the use of force in enforcing U.N. Security Council resolutions such as UNSCR 2249, which specifically referenced Iraq in the context of the threat posed by the Islamic State. But even this interpretation rests on shaky grounds when considering the preamble of the 2002 AUMF, which references a series of specific UNSCRs from the 1990s aimed at the threat posed by Saddam Hussein’s regime.

To the Obama administration’s credit, it was clearly aware of the problematic nature of reliance on these AUMFs. In his Jan. 2015 State of the Union address, President Obama called on Congress to enact a new AUMF specifically targeting the Islamic State. In Feb. 2015, the president also delivered a draft AUMF to Congress that would have authorized the continued use of military force to degrade and defeat ISIS, without permitting long-term, large-scale ground combat operations. The draft AUMF was never adopted by Congress, and to date (despite ongoing efforts to repeal or replace them) the 2001 and 2002 AUMFs remain in force. They remain the principal legal basis under U.S. domestic law for continued military action in Iraq.

Operations Targeting Iranian-Backed SMGs

International Law. Up to this point, this article has considered the legal basis for U.S. operations in Iraq against ISIS. But since at least 2017 – and particularly from 2019 onwards – the United States has become increasingly drawn into a series of tit-for-tat strikes with local SMGs and other Iranian proxies. U.S. forces and supporting elements have been subject to hundreds of short-range rockets, dozens of suicide drones, and frequent roadside bombings. Since late 2019, five U.S. citizens, including three U.S. soldiers (along with one British soldier) have been killed in Shia militia group attacks on U.S. bases in Iraq.

When the United States has responded to these attacks, airstrikes have generally followed either a particularly heavy series of militia attacks, or an attack which caused U.S. casualties. To date, the White House has acknowledged airstrikes on Iran-backed Shia militia groups on Iraqi soil on four occasions; once under President Biden (June 27, 2021), in addition to three occasions in December 29, 2019, January 3, 2020, and March 13, 2020 under President Trump. Other than the January strike (which targeted Qasem Soleimani and his entourage), each occasion involved airstrikes on multiple militia facilities.

Unlike U.S. operations in Iraq against ISIS, U.S. operations against Iranian proxies are legally murky. First, it is not at all apparent whether Iraqi consent extends to these strikes. Indeed, Iraq has publicly condemned U.S. attacks on SMGs on its soil. After the drone strike that killed Soleimani and Muhandis in Jan. 2020, then-Prime Minister Abdul-Mahdi called the killings “an act of aggression on Iraq and breach of its sovereignty” and noted that they “violated the conditions of U.S. military presence in Iraq.” After the airstrikes in June 2021 on Kata’ib Hezbollah and Kata’ib Sayyed al-Shuhada, the Iraqi government called the U.S. attacks “blatant and unacceptable violation of Iraqi sovereignty and national security.” Meanwhile, strikes on many SMGs – despite their fierce loyalty to, and support from Iran – are arguably armed attacks on the Iraqi state itself, since (as noted above) most SMGs are also part of the Iraqi security forces through the PMF. SMGs and their supporters use this status as a propaganda tool, condemning all U.S. strikes on their forces as attacks on Iraqi sovereignty, and demanding government action (and further militia retaliation) against the United States as an alleged illegal occupying force.

While the terms of U.S.-Iraqi cooperation permit the United States to defend itself from attacks, Iraqi public statements suggest that the Government of Iraq rejects U.S. justifications of at least some of these strikes as necessary for purposes of self-defense. It should be noted that many in the current Iraqi administration are genuinely sympathetic behind closed doors to the predicament this places U.S. forces in – but are compelled to condemn the strikes publicly for fear of militia retaliation – and it is impossible to rule out Iraqi consent given behind closed doors.

Nevertheless, the United States has publicly justified its strikes on these militias as “necessary and proportionate action consistent with international law… in the exercise of the United States’ inherent right of self-defense as reflected in Article 51 of the United Nations Charter.” Questions remain, however, as to whether U.S. airstrikes after militia attacks fall within the scope of the inherent right to self-defense in the absence of an imminent or ongoing attack. Successive U.S. administrations have put forward increasingly expansive interpretations of what constitutes an “imminent” attack, which has effectively elongated the temporal aspect of imminence, and (under U.S. interpretations) permits the use of force in self-defense based on a pattern of violence (rather than a temporally imminent attack). But these strikes against SMGs in Iraq (and Syria) seem to go a step further, with public U.S. statements focused more on past attacks than future planning.

The Trump administration’s justification for the killing of Soleimani and Muhandis noted that the strike was “in response to an escalating series of attacks.” The Biden administration’s language is more cautious, but still alludes to airstrikes occuring in response to militia rockets, claiming for example that “[g]iven the ongoing series of attacks by Iranian-backed groups targeting U.S. interests in Iraq, the President directed further military action to disrupt and deter such attacks.” Given U.S. airstrikes against the militias have not always occurred in the immediate aftermath of a significant rocket or drone attack on U.S. forces (generally, they occur days after those attacks where the U.S. suffered casualties), some observers have noted that the strikes appear to be carried out as reprisals. As Mary Ellen O’Connell has observed, while international law does permit the use of force in self-defense, there is no right of reprisal. And Adil Ahmad Haque has pointed out that even a proportionate military response to a previous armed attack, that is clearly over, is not proportionate self-defense but an armed reprisal.

U.S. Domestic Law. If the international legal basis for strikes on SMGs is thinner than that of counter-ISIS operations, the U.S. domestic law is particularly tenuous. The Trump administration based its strike on Soleimani and Muhandis on the president’s Art. II powers and the 2002 AUMF. With respect to the latter, the Trump administration argued that U.S. “uses of force [under the 2002 AUMF] need not address threats from the Iraqi government apparatus only, but may address threats to the United States posed by militias, terrorist groups, or other armed groups in Iraq.” This argument has been roundly criticized. Previous U.S. administrations explicitly rejected the idea that the 2002 AUMF applied to Iran (as it was designed for “defend[ing] the national security of the United States against the continuing threat posed by [Saddam Hussein’s] Iraq” [emphasis added]). To be clear, the Government of Iraq today is a strategic U.S. security partner – and not an aggressor seeking harm to the United States.

To its credit, the Biden administration did not claim the 2002 AUMF provided authority for its strikes on the SMGs. Instead, Biden’s strikes have been justified on the basis of the president’s authority under Art. II of the Constitution. But the preemptive nature of U.S. attacks – along with the cyclical pattern of hostilities in both Iraq and just over the border in Syria – raises the possibility that this conflict may reach a threshold of “war in the constitutional sense” – that is, where prior congressional authorization is required based on Congress’ explicit Art. I authority to decide when the nation goes to war. The Biden administration has reported strikes against SMGs as discrete actions, ostensibly each triggering its own 60-day termination clock under the War Powers Resolution. In general, Art. II authority has been interpreted to allow short, limited uses of force – but sustained engagements require congressional authorization. Over the last few months, SMG operations against the United States have decreased (probably due to a combination of Iraqi domestic political maneuvering, Iranian restraint, and Ramadan). If the attacks resume in the near future (which many analysts believe is likely) then it is possible future U.S. military operations against Iranian-backed groups in Iraq would cross the threshold for requiring congressional authorization in the form of a new AUMF.

What Next?

There are both benefits and risks to maintaining a U.S. military presence in Iraq. While ISIS has been defeated territorially, the group could resurge with little warning. Absent continued U.S. support, local ISF forces may not be able to deal effectively with a potential ISIS resurgence. At the same time, the continued U.S. military presence in Iraq risks escalation with Iran, particularly in light of the repeated tit-for-tat attacks between U.S. forces and Iranian-backed SMGs, which the government of Iraq has itself been unable to fully control.

Overall, there are strong policy imperatives for maintaining a limited U.S. military presence in Iraq to ensure Iraqi stability and counter Iranian influence. While few acknowledge it publicly, given domestic political sensitivities, many Iraqi government officials support the continued U.S. presence in Iraq as a counterweight to Iranian – and SMG – influence. Iraqis categorically do not want to be a U.S. vassal or return to the days of the U.S. occupation – but nor do most Iraqis want to be dominated by their neighbor. This fear of Iranian clienthood is strong among Sunnis and Kurds, but also increasingly among Shi’ites, many of whom supported protests against Iranian-backed militias and politicians in recent years. SMGs are reviled by many Iraqis for their corruption, their killing of protestors, journalists (and even investigating government officials), and the impunity under which they act. Iraqi government efforts to investigate and control these groups are hampered by SMG military strength and their entrenched position in Iraqi public life. U.S. support for Iraqi intelligence, law enforcement, and the judiciary is crucial in preventing SMGs from consolidating their power in Iraq. In short, U.S. interests in a stable Middle East are not served by allowing Iran and its proxies to consolidate control in Iraq, which could allow SMGs to become expeditionary like Lebanese Hezbollah, or could spark further regional tensions in the Gulf. Iraq’s future as an imperfect but functioning democracy subject to the rule of law is also unlikely to be served by allowing greater Iranian and SMG control.

The fact remains, however, that countering Iran and the SMGs is not the stated or legally authorized purpose for the U.S. deployment in Iraq. The United States must not allow itself to slide into any new ill-defined conflict with Iran (or with the SMGs) based on art. II authorities, outdated AUMFs, and stretched interpretations of the right to self-defense. To the extent it can do so by non-military, diplomatic means (and with the consent of the Iraqi government), the United States should continue to support Iraqi law enforcement efforts to counter illegal activities (including the targeting of U.S. personnel and equipment), while strengthening the Iraqi judiciary to ensure arrested militiamen are ultimately convicted. Meanwhile, so long as the counter-ISIS mission remains legally sound and consented to by Iraqis, the United States also should not allow Iranian and SMG attacks to force it to abandon its partners in Iraq.

To the extent that the United States resorts to force in Iraq going forward, whether against ISIS or against other actors, an urgent conversation must be had over domestic U.S. authorization for that force. To resolve this problem while supporting U.S. security interests, its allies, and its respect for the rule of law, the U.S. administration and Congress should rescind the outdated 2001 and 2002 AUMFs and carefully consider whether a new authorization designed to meet today’s security challenges in Iraq is necessary.

Image: U.S. vehicle is pictured at a military base in Rumaylan (Rmeilan) in Syria’s northeastern Hasakeh province on July 28, 2020 (Photo by DELIL SOULEIMAN/AFP via Getty Images).