With the targeted killing of Iranian Maj. Gen. Qassem Soleimani on Thursday, President Donald Trump has dramatically escalated hostilities with a militarily sophisticated foreign government, engaged in a highly controversial use of force in the territory of Iraq without its consent, and changed the U.S. security posture in the region and beyond, all without first consulting Congress let alone obtaining congressional approval.

The Trump administration sent Congress a classified letter Saturday under the War Powers Resolution, which requires that Congress be notified within 48 hours of presidential action introducing U.S. forces into hostilities. House Speaker Nancy Pelosi has characterized the notification as prompting “serious and urgent questions about the timing, manner and justification of the Administration’s decision to engage in hostilities against Iran.” While these reports are often brief, the law requires the president to explain the legal justification for the action along with other key information. For an action this momentous, the Trump Administration owes the American public and the Congress an unclassified explanation.

Did President Trump have the authority to take such a significant military action without going to Congress first? And what is the role of the War Powers Resolution, which some have erroneously cited as authorization for the strike, after the fact?

The following examines these and related questions, and previews the upcoming publication of a searchable database analyzing the contents of all 48-hour reports submitted to Congress since the War Powers Resolution’s enactment. The database, created under the auspices of NYU Law’s Reiss Center on Law and Security, will be a living resource intended for use by policymakers, legislators, scholars, journalists and others who are interested in how presidents use U.S. armed forces abroad, across all administrations and in different parts of the world.

Did Congress Authorize the Soleimani Strike?

A threshold question for the War Powers Resolution is whether Congress has already authorized the military action. If there is such congressional authorization, the executive branch has long claimed it does not need to submit a 48-hour report. So is there any prior congressional authorization for the strike against Iranian General Soleimani?

The administration has informally provided competing legal justifications for the Soleimani strike, making clear the need for an unclassified formal accounting on this score. National Security Adviser Robert O’Brien has claimed the strike was “authorized” in part by the 2002 Authorization for Use of Military Force (2002 AUMF). That claim has no merit. As Brian Egan, a former State Department Legal Adviser and former Legal Adviser to the NSC, and I have explained at Just Security, there is “no viable argument” that the 2002 AUMF authorizes force against Iran. As we wrote, that statute:

allows the President to “defend the national security of the United States against the continuing threat posed by Iraq;” and “enforce all relevant United Nations Security Council resolutions against Iraq.” Those are plainly not relevant to the situation with Iran today. (emphasis added)

The State Department acknowledged as much in a June 2019 letter to Congress in which it said the administration had not concluded that the 2001 or 2002 AUMFs would authorize force against Iran. But the department left one big caveat. The State Department’s letter claimed either AUMF could potentially be used if “necessary to defend U.S. or partner forces engaged in counterterrorism operations or operations to establish a stable, democratic Iraq.” Ryan Goodman and I explained what this means in practice for a potential use of force against Iran:

It means the Administration believes it could use force against any party — Iran, Syria, Russia, Hizbollah, other militias or armed groups — that threaten ongoing U.S. operations authorized by the 2001 or 2002 AUMFs, so long as those third parties present an imminent threat to U.S. or partner forces engaged in those operations. This could include, for example, U.S. military action against Iranian or proxy forces in Iraq or Syria, if the Iranian-aligned forces engaged in a direct attack on U.S. or partner forces in those theaters.

This argument, as Ryan and I noted, is at best a slippery slope. But as articulated by the Trump Administration last summer, it should have at least been limited to the potential use of force in the context of operations against ISIS or al-Qaida. That does not appear to be the case with the U.S. strike on Soleimani last week. And indeed, justifications that senior U.S. officials such as the Secretary of State have given — such as Soleimani’s threat to U.S. diplomats and citizens in other parts of the region — have no connection to the U.S. counter ISIS operations. Moreover, the strike is likely to make it more difficult to keep a strong U.S. presence in Iraq for future counter-ISIS operations – Iraq’s parliament has already voted to expel U.S. troops from the country in response to the strike (which also killed Iraqi military personnel).

The Constitutional Question

CNN has reported that the administration “concluded it didn’t need congressional sign off from a legal standpoint” for the Soleimani strike, because it believes the president’s commander-in-chief authority under Article II of the Constitution was sufficient to take this action unilaterally.

A key question in the executive branch’s legal test for when the president can undertake a unilateral use of force without congressional authorization is whether the action would constitute “war”– the Constitution clearly gives the power to declare war to Congress, as even the executive branch acknowledges. But what constitutes “war” in the “constitutional sense?” According to a 2018 Office of Legal Counsel (OLC) opinion on the Trump Administration’s strikes in Syria, if the expected “nature, scope, and duration” of a military engagement falls below a certain threshold — generally characterized by “prolonged and substantial military engagements, typically involving exposure of U.S. military personnel to significant risk over a substantial period” — the “war” threshold is not reached and the president has unilateral authority to act without congressional authorization.

It has long been clear that this test “imposes very little constraint on modern presidential uses of force” (as Curt Bradley and Jack Goldsmith wrote in 2018). In theory, however, it has some remaining limits. As Brian Egan and I noted in this Just Security backgrounder:

The threshold for “war” in the constitutional sense is more easily met when the use of force at issue is against another nation state (rather than in its territory but with its consent) where there is a high likelihood of escalation. Although Iran is not a nuclear power, which would necessarily affect that calculus, its capacity as a nation-state with a strong military, including its cyber and ballistic missile capabilities, are relevant factors in this analysis, as is the extent of U.S. exposure given its significant footprint in the region where Iranian military forces (and their proxies) are present and active.

Those limits are clearly relevant in the Soleimani strike. The use of force was against Iran — not a proxy force whose actions are attributable to Iran — and specifically against a most senior official of that sovereign country. There clearly was and remains a high likelihood of escalation, with both countries already threatening further action against the other. President Trump has already threatened via Twitter to strike 52 targets in Iran – notably in a manner that would constitute a war crime – which have their own way of spiralling into further tit-for-tat reprisals. The Pentagon also has said it will send 3,500 additional troops to the Middle East “after Iran vowed to exact ‘severe revenge.’” And in anticipation of future violence, the United States has warned its citizens to leave Iraq in an extraordinary “do not travel” advisory. From the opposing side, rockets already have been fired at bases in Iraq housing U.S. forces. And Adil Haque notes Iran’s letter to the United Nations treats the killing of Soleimani as a “terrorist attack,” an “assassination,” and “a criminal act” (the letter argues the strike was “aimed at escalating tensions to an uncontrollable level in a region already facing numerous challenges.”)

Congress need not acquiesce in the executive branch’s interpretation of the president’s unilateral Article II authority. As Brian Egan and I noted in our overview of the debate over the contours of the president’s constitutional authority to initiate force without Congress, the executive branch over several administrations of both political parties has taken a broad view of the President’s unilateral authority, while “Congress does not necessarily view its own authority so narrowly or the president’s so expansively.” In my view, Congress can and should assert its own interpretation and articulate far more concrete constraints than those offered by successive Office of Legal Counsel lawyers.

But even accepting the executive’s own test, this case should meet the threshold for a use of force that required congressional authorization. If it does not, it’s hard to imagine what type of scenario — barring a major land invasion of a foreign country — would make the executive branch acknowledge it needs congressional authorization.

How Does the War Powers Resolution Fit In?

President Trump has claimed he “took action… to stop a war. We did not take action to start a war.” Most experts appear to disagree. While all of the consequences may not be felt right away, Trump’s action is likely to set off an escalatory cycle of violence. The War Powers Resolution is intended to ensure Congress has a say in exactly this question: when should the nation go to war, or get itself into a situation where war is likely?

One of the War Powers Resolution’s key provisions is intended to create transparency when presidents use our armed forces abroad without statutory authorization, or at least to ensure congressional knowledge. Specifically, it requires presidents to notify Congress within 48 hours of undertaking certain military actions abroad, and to articulate the legal basis for the action, the circumstances “necessitating” the action, and its “estimated scope and duration.” If the use of armed forces involves an introduction into “hostilities” or imminent hostilities (a debated term undefined in the statute), the president is required to stop the activity after 60 days (extendable to 90 in limited circumstances) unless Congress has authorized it. And, as noted above, the War Powers Resolution explicitly states that it does not provide the president with independent authority to use force. It is a constraint, not a source of power.

What should we make of the Trump administration’s highly unusual decision to classify its 48-hour notification to Congress? The law doesn’t explicitly require that these notifications be submitted in unclassified form. But doing so forces the transparency that the 48-hour reporting intended to provide. Fully classifying the justification makes it much harder for the public to engage their elected representatives from an informed position, and indeed, makes it much harder for members of Congress to engage on the issues in public. Especially given the administration’s inability thus far to articulate a coherent legal rationale for the Soleimani strike — while officials are nonetheless willing to make statements on the record — the administration should put forward an unclassified version of its report as soon as possible. (The administration also should heed reporting requirements under other statutes that I won’t delve into here).

Whether classified or not, the combination of the required 48-hour reporting and the 60-day countdown to termination of hostilities could create a meaningful lever for Congress going forward. To be sure, the administration is likely to argue that “hostilities,” as that term is understood for War Powers Resolution purposes, concluded when the strike was completed (as presidents have argued with targeted strikes in past instances), and thus that the 60-day clock is no longer ticking. (For more on that type of justification, see Todd Buchwald’s analysis at Just Security.) But that argument here would ignore the facts already unfolding in the direction of more violence and new troop deployments, as well as any future hostilities that are quite likely to occur over what may be an extended period of time.

If Congress does want to stop the President from bringing us further toward a war with Iran, the War Powers Resolution is not the only — and indeed may not be the best — mechanism to use. The War Powers Resolution has significant gaps (such as the lack of a definition of “hostilities”) and has been weakened over the decades, as Steve Pomper and I discussed in this Policy Roundtable. Perhaps most important for future action by Congress following the Soleimani strike is the factor of a presidential veto, as Brian Egan and I explained:

[R]ecent experience has shown that unless Congress has sufficient votes to override a presidential veto of a resolution requiring termination of the use of U.S. Armed Forces, it may be unable to stop military engagement abroad once it has begun using the mechanism of the WPR alone, so long as the president believes that the military engagement in question does not constitute “hostilities.”

While difficult to overcome a likely veto, the War Powers Resolution does at minimum ensure congressional debate. Sen. Tim Kaine (D-Va.) has introduced a resolution that would require removal of U.S. forces from hostilities with Iran under “privileged procedures” in the War Powers Resolution that require the full Senate to debate the issue and take a vote. While the President, as a formal matter, may be able to block a congressional war termination by exercise of a veto, as an informal matter that step (having to exercise the veto) may well mark the political end to a war. It would be difficult to sustain the legitimacy of the operations. Beyond the War Powers Resolution, Congress can also consider a funding cut-off, relying on its appropriations power, which is a core constitutional authority that the executive branch would be hard pressed to ignore.

Regardless of what action Congress might take going forward, the War Powers Resolution’s 48-hour reporting function has already played a fundamental role: It ensures Congress has information, quickly, that can be used for continued oversight, even if that information simply indicates that there are many more questions to pursue.

A 48-Hour Reports Database

The Trump Administration’s reporting practice under the War Powers Resolution, particularly with respect to this latest fully classified report, is situated within the larger context of presidential reporting since the enactment of the statute in 1973. NYU Law School’s Reiss Center on Law and Security–where I am a Senior Fellow and Visiting Scholar–will soon be launching the first publicly-available (and easily searchable) database analyzing the contents of all unclassified notifications of the use of U.S. armed forces abroad (“48-hour reports”) that presidents have provided to Congress under the War Powers Resolution since its passage nearly half a century ago. I served as lead researcher and author for the project, which includes an analysis of key findings from the data.

The project’s analysis of more than 100 of these 48-hour reports aims to answer key questions about presidential exercise of war powers over the last 45 years: Where and why are presidents deploying U.S. armed forces abroad? How often do presidents rely solely on their own constitutional authority to do so, and is that authority being stretched? Has reporting fulfilled the War Powers Resolution’s requirements? In what ways are those requirements insufficient to inform Congress of how the president is using our armed forces abroad, and in what ways is the WPR succeeding in providing meaningful transparency?

Interactive graphics, along with initial key findings drawn from analysis of the database, will accompany the searchable database. That analysis can help us determine, among other things, whether new reports are in line with general practice, or in what ways they might differ.

For example, analysis of existing reports demonstrates that over half of the 48-hour reports provide enough information to identify an international legal basis for the reported activity, even though doing so is not required by the text of the War Powers Resolution. Reports are most likely to provide an international law basis when they mark the introduction of U.S. armed forces into hostilities or circumstances in which hostilities are imminent — arguably where the stakes are highest and where the international legal basis for the activity is most likely to be at issue.

My assessment of the Soleimani strike in this essay does not address the important international law questions about the operation. Unfortunately, because it is classified, we cannot evaluate how the 48-hour report Trump provided to Congress on Saturday measures up against prior reporting practice(Leader Pelosi’s statement seems to indicate a bare-bones notification). Whether the executive branch can show that it had a valid claim of self-defense in striking Soleimani, or perhaps believes it is already in an armed conflict with Iran that would render him a legitimate target, are crucial questions that Congress and the public should press the administration to answer publicly. These are a few of the many questions for which the American public now deserves to have answers as events in response to the Soleimani strike continue to unfold in the weeks and months and, indeed, many years ahead.