The escalating tension with North Korea reminds us once again that in matters of war and peace, there are often no good options. But that does not mean that there aren’t particularly bad, even catastrophic options. That is why the founders divided constitutional war-making authority, granting Congress alone the power to declare and fund wars, while making the president the commander-in-chief of the armed forces. Decisions about going to war may be so difficult that Congress at times would rather sit them out, but weighing in on potential new wars is a constitutional responsibility, not an elective activity.

That’s why, in the wake of President Trump’s strikes against the Syrian government earlier this year, we at Protect Democracy demanded to know the president’s legal justification. The debate about war powers has gone on for decades, but prior presidents have felt obligated to at least explain their legal justification for military action. We filed FOIA requests, and when the administration refused to comply, we went to court ― and have already won a preliminary decision. We took no position on the wisdom of the strikes themselves, and many in Congress and in the public may have supported the strikes, but as U.S. District Court Judge Christopher Cooper put it in his ruling, “Being closed off from such a debate is itself a harm in an open democracy... Military strikes cannot be undone.”

Now, even as we work through the schedule to obtain those Syria documents, the court’s words ring like alarm bells. As the prospect of a nuclear conflict looms, even if in the distance, the president continues to act as if decisions of war and peace are his alone to make. And though some in Congress express comfort in the generals the president has surrounded himself with, there are now reports that Trump’s own national security team was caught unaware when he dramatically escalated tensions with his “fire and fury” comments. (We’re filing a new round of FOIA requests on Trump’s legal authority to strike North Korea today.)

There has already been movement to reassert Congress’s war powers. Even before the escalation with North Korea, the House embraced an amendment to demand a new war authorization for the fight against ISIL (it was later stripped from the legislation behind closed doors by Speaker Paul Ryan). And now, in addition to senators of both parties raising concerns about the president’s escalating rhetoric, Republican Senator Dan Sullivan of Alaska stated flatly, “if one of the military options that the administration is looking at is a preemptive war on the Korean peninsula launched by the United States, that would require the authorization of Congress,” adding that “Article I of the U.S. Constitution is very clear about that.”

It is probably no coincidence that the most definitive demand for a vote came from one of the states that is geographically closest to North Korea. With a volunteer army increasingly bearing the burden of wars with their families outside the direct experience of most Americans, including most Members of Congress, decisions to enter military conflicts can increasingly seem like an abstract policy debate. But it should not take the vivid image of a nuclear missile aimed at one’s state for Congress to fulfill the responsibilities that the founders placed in them.

The president could actually bolster his own authority if he went to Congress and got support for any actions he pursues against North Korea. Under the famous framework laid out by Justice Jackson in the 1952 Youngstown Steel Seizure case, the president’s powers are at their zenith when he has Congress behind him. As Justice Jackson’s concurring opinion explained: “When the President acts pursuant to an express or implied authorization of Congress, his authority is at its maximum, for it includes all that he possesses in his own right plus all that Congress can delegate. In these circumstances, and in these only, may he be said (for what it may be worth) to personify the federal sovereignty.”

On the flip side, if other members of Congress share Sen. Sullivan’s fears, they can constrain the president. As Justice Jackson put it, “When the President takes measures incompatible with the expressed or implied will of Congress, his power is at its lowest ebb, for then he can rely only upon his own constitutional powers minus any constitutional powers of Congress over the matter.” While the Court’s language looks to legal constraints that Congress may impose, strong statements from members of Congress can create a powerful political check as well.

As it stands now, with Congress neither authorizing nor forbidding action against North Korea, we stand in what Justice Jackson called the “zone of twilight.” As he explained: “congressional inertia, indifference or quiescence may sometimes, at least, as a practical matter, enable, if not invite, measures on independent presidential responsibility.”

With nuclear war being threatened, and dangerously unpredictable men holding power in the U.S. and North Korea, the stakes are simply too high for Congress to leave things to the president. President Trump’s apparent view that he alone can start new wars stands as an open breach in our democracy, and he is making decisions based on this misunderstanding by the day, with potentially unimaginable consequences. President Trump must acknowledge the role of Congress, not continue to act as if he alone holds all war-making powers.

If the president continues on this misunderstanding, Congress can, and must, correct him before it is too late. There are many ways for Congress to do this, both formally and informally. Congress can hold hearings on legislation like the bill introduced earlier this year requiring congressional approval for nuclear first strikes. It can consider legislation to prohibit (or authorize under specific conditions) the preemptive use of force against North Korea. It can conduct oversight through document requests and hearings with witnesses from the administration to better understand the president’s strategy or views of his legal authority. Or members of Congress can serve as a strong political restraint by joining Sen. Sullivan in speaking out forcefully against the president’s view that he alone can choose to start a war. Whatever path Congress takes, it is time for members to engage ― this is not an elective activity, it’s their job.