Since announcing its intent to leave the Intermediate-Range Nuclear Forces Treaty late last year, the Trump administration has tried to portray this move as the inevitable result of Russian malfeasance. U.S. Ambassador to Russia Jon Huntsman has described it as “a forced decision” necessitated by Russia’s insistence on “producing, flight-testing, and fielding exactly the type of [intermediate-range] missile that the INF Treaty prohibits.” “If the INF Treaty dies,” U.S. Ambassador to NATO Kay Bailey Hutchison has similarly argued, “blame Russia…A treaty cannot exist when one side complies and the other does not.”

Russia’s violations of the INF Treaty are real and should be of serious concern. But this narrative obscures the exceptional nature of the response that the Trump administration is pursuing by not only suspending U.S. compliance with the INF Treaty but leaving it altogether. And this framing ignores the fact that President Trump is planning to take this latter step in spite of opposed legislation that Congress has enacted over the past several years—something that may well make his actions vulnerable to constitutional challenge.

Secretary of State Mike Pompeo took the first step towards exiting the INF Treaty on Feb. 1, when—with support from NATO allies—he declared Russia to be “in material breach of its obligations not to produce, possess, or flight-test a ground-launched, intermediate-range cruise missile system with a range between 500 and 5,500 kilometers” under the INF Treaty. Under international law, Russia’s material breach entitles the United States to partially or wholly suspend its own participation in the treaty, which Pompeo did. As a result, so long as Russia remains non-compliant, the United States may resume any activities that the INF Treaty might have otherwise prohibited.

But Pompeo did not stop there. He also announced that the United States was starting the six-month process for withdrawing from the INF Treaty, a separate remedy that Article XV of the treaty permits where “extraordinary events”—identified by Pompeo as “Russia’s continued noncompliance”—have “jeopardized [a party’s] supreme interests.” Once complete, this withdrawal will irrevocably end U.S. participation in the INF Treaty, effectively terminating the agreement. The Trump administration, however, has left open the possibility that it will not go through with withdrawal if Russia resumes compliance before the Aug. 2 implementation date.

Suspension alone would allow the United States to respond in kind to any material breach by Russia. Withdrawal will go further by permanently removing the INF Treaty’s obligations and delinking U.S. policy options from future Russian conduct. This will not help efforts to bring Russia back into compliance. But it’s a desirable outcome for those who view the INF Treaty as an outdated constraint on U.S. strategy that sets undue limits on its ability to respond to rising states that are not covered by the treaty, like China and Iran. In this sense, the Trump administration appears to be capitalizing on Russia’s violations to advance these broader strategic objectives—the exact approach that National Security Advisor John Bolton recommended before he joined the administration.

A Major Problem

One can debate the merits of this approach on policy grounds. As a legal matter, however, it faces a major problem: Congress does not appear to be on board.

Since 2014, Congress has repeatedly enacted legislation expressing concern over Russia’s INF Treaty violations and calling for efforts to pressure Russia back into compliance. At times, this legislation has even included mandatory directives and requirements intended to advance this objective. Moreover, since 2017, Congress has explicitly endorsed the view that Russia’s material breach warrants suspension, leaving little doubt that it supports this step.

But this is not true of withdrawal. In all this relevant legislation, Congress has only mentioned withdrawal once and never endorsed it. To the contrary, many of the measures that Congress has put forward or endorsed that are aimed at restoring Russian compliance would be rendered moot if the INF Treaty were terminated. While it never says so explicitly, the clear implication is that Congress opposes withdrawal—a point brought home by the 2017 legislation, which lawmakers entitled the “Intermediate-Range Nuclear Forces (INF) Treaty Preservation Act.”

Why does this matter? Because it is unclear who precisely has the legal authority to withdraw the United States from treaties. Like other recent presidents, Trump has claimed the authority to do so on his own without consulting Congress. But no president has ever taken this step in the face of contrary legislation. Under the Youngstown framework that courts often apply to resolve such inter-branch disputes, the president may only take such actions when they are within his exclusive constitutional authority. And given that the Constitution is silent on treaty withdrawal, this may be a difficult argument for Trump to make.

This constitutional vulnerability may in turn lead to a legal challenge to the president’s withdrawal decision. While similar challenges have failed to reach the merits in the past, none have involved such a well-established record of congressional opposition, a record Congress could strengthen further by making its opposition even more explicit. And while any plaintiffs’ success would be far from guaranteed, the risk—both to the Trump administration’s policy towards the INF Treaty and to its control over treaty withdrawal—is substantial enough to warrant careful consideration.

For these reasons, the Trump administration would be well-advised to address these legal vulnerabilities the only way it can: by coordinating with Congress. If policy-makers are confident in the case for withdrawal, then they should ask Congress to make clear it has no objections before Aug. 2. This would also make the threat of withdrawal more credible, which may improve the chances that Russia will be persuaded to resume compliance before that deadline arrives.

Otherwise, the Trump administration may wish to limit itself to suspension, a move endorsed by Congress that does not raise the same legal concerns. This would still provide the United States with extensive flexibility in responding to Russian violations. But it would leave the question of the INF Treaty’s ultimate demise—and the broader strategic considerations it implicates—for future generations to decide.