The problem is not simply that congressional leaders won’t stop President Trump from firing Deputy Attorney General Rod Rosenstein, and maybe Special Counsel Robert Mueller, and plunging America into a constitutional crisis. The problem is that those congressional leaders—while allowing Trump to do all this—are also allowing him to take the United States to war.

On Wednesday morning, Trump tweeted: “Russia vows to shoot down any and all missiles fired at Syria. Get ready Russia, because they will be coming, nice and new and ‘smart!’ You shouldn’t be partners with a Gas Killing Animal who kills his people and enjoys it!”

That tweet capped an eventful 24 hours. On Tuesday, as CNN was reporting that Trump might fire Rosenstein, The New York Times reported that, in response to the Syrian government’s apparent chemical weapons attack over the weekend, “Administration officials said they expected any new [American] strike to be more expansive than last year’s.” That’s both predictable, and frightening. The more expansive the attack, the more likely it is to hit not only the Syrian government, but also its Russian and Iranian allies.

John Bolton, Trump’s new national-security adviser, has long argued that for the U.S. to intervene effectively against Syrian dictator Bashar al-Assad, “U.S. intervention could not be confined to Syria and would inevitably entail confronting Iran and possibly Russia.” And Trump himself on Monday pointedly suggested that Moscow and Tehran might share responsibility with Damascus for the chemical-weapons attack. On Tuesday, Russia’s UN ambassador responded by threatening “grave repercussions” if the U.S. again strikes the Syrian government. Russia’s ambassador to Lebanon warned that, “If there is an American strike, then we … will shoot down rockets and target the positions from where they were launched.”

Constitutionally, Trump has no authority to launch another war. The Constitution gives that power to Congress. When President Obama launched attacks against the Islamic State, his administration cited a law Congress passed on September 18, 2001, which authorized force against “those nations, organizations, or persons” involved in 9/11. That was dubious enough, given that the Islamic State didn’t exist in 2001. But claiming that authorization justifies striking Syria for using chemical weapons is absurd.

So absurd, in fact, that when the Trump administration attacked Syria last year, it didn’t even pretend that Congress had given it the go-ahead. Instead, Secretary of State Rex Tillerson said, “The President authorized that strike pursuant to his power under Article II of the Constitution as Commander in Chief and Chief Executive to use this sort of military force overseas to defend important U.S. national interests.” Even previous presidents, noted Harvard Law School professor Jack Goldsmith, who ran the Justice Department’s Office of Legal Counsel under George W. Bush, had not asserted such sweeping authority. The Trump administration’s claims, he argued, “provide no practical limitation on presidential power.”

It’s not surprising that a president who thinks the Justice Department should act as his personal law firm, and the FBI should act as his personal security detail, would claim unlimited personal authority to wage war. But it’s especially disturbing because Trump’s motivations for launching a war are more suspect than those of any president in modern history. One of his biographers, Gwenda Blair, has noted “his trademark tactic of distraction and misdirection”—his career-long habit of launching dramatic stunts or spats to turn attention away from unpleasant news. In March, former CIA Director John Brennan—who is not given to hyperbole—warned that Trump might “try to distract the attention here domestically and politically on him and engage in some type of international initiative that is going to really put our nation at risk.”

It would be wrong for Congress to allow any president, on his own authority, to launch an attack on Syria that potentially puts the U.S. in conflict with Russia, Iran, or both. But granting that power to Trump—as he contemplates a second Saturday Night Massacre—is utter lunacy.

Yet with a few exceptions like Senators Mike Lee and Rand Paul, Republicans in Congress appear determined to do just that. Bob Corker, the chairman of the Senate Foreign Relations Committee, declared on Monday: “If the administration goes against [Assad], which I hope they will, I think it will be something very surgical. That is not something that, to me, warrants an AUMF [Authorization of Use of Military Force].” It’s comforting that Corker can read Trump’s mind. Let’s just hope his definition of “surgical” is the same as Vladimir Putin’s.

Since Trump took office, there’s been endless talk about his refusal to abide by the norms that have restrained previous presidents. But when it comes to making war, Trump isn’t disregarding a limitation on presidential power. He’s taking advantage of the fact that no such limitation exists. He’s walking through a door that congressional leaders of both parties have self-consciously left open in the post-9/11 era because they haven’t wanted to take responsibility for America’s wars. And so, even as Trump contemplates igniting one constitutional crisis, he perpetuates another.