The U.S. missile strike on a Syrian government airfield Donald Trump ordered yesterday to retaliate for Bashar Al-Assad’s latest chemical attack on his own people fell on the 100th anniversary of America’s entry into World War I—the conflict that pretty much wrote the ghastly script for the rest of the 20th century, from the Bolshevik revolution that gave us the USSR to the rise of Nazi Germany. World War I was also the United States’ debut on the international stage as a self-appointed world savior—the sometimes valiant, often bungling role that has only sporadically won us the rest of the planet’s hosannahs. But Trump isn’t a man who gets rattled by historical coincidences.

While it isn’t all that likely that our stepped-up intervention in Syria will trigger World War III, that country is currently the world’s foremost tinder box, with Russia, Turkey and Iran, along with the U.S., all having skin in the game. That means you never know.

Four years ago, Barack Obama was widely condemned for his failure to punish Assad for a similar (and more deadly, numbers-wise) chemical attack on a rebel-held suburb of Damascus, especially because Obama had earlier declared that the use of such weapons was a “red line” the tyrant had better not cross. But we may yet learn to feel nostalgic for 44’s calculated reticence, no matter how unattractive it seemed at the time. Trump’s reversal of that policy bristles with potential danger signals for both his presidency and the world’s tranquility. Here are the top three.

Even though our allies were apparently notified of the attack, it seems no serious effort was made to enlist them as partners—not even Great Britain, our most reliable Mini-Me. Nor did Trump look to either NATO’s framework or a United Nations resolution to provide a figleaf of international backing. He might not have gotten it, but at least he would have been able to say he tried.

His ratings are in the toilet. Russiagate is dogging him. His legislative agenda is D.O.A. He’d love to distract us.

Trump also didn’t ask for Congressional authorization, which he almost certainly would have gotten. Back in 2013, ironically enough, he tweeted that Obama would be making a “big mistake” if he attacked Syria without Congressional approval. (In fact, Obama’s inability to obtain it was his somewhat disingenuous excuse for erasing the “red line” he’d proclaimed the year before.) Just like the predecessor he reviled, Trump is relying exclusively on the resolution authorizing the use of military force that Congress passed 16 years ago in the wake of 9/11. Aimed at Al-Qaeda, it has since been the increasingly tenuous justification for three presidents’ military activism all over the Middle East.

How much does this matter? Kind of a lot. True, the U.S. is always the big dog in any nominal “coalition of the willing” (in Dubya’s immortal formulation) we cobble together and just about guaranteed to get its way. At home, Congress essentially abdicated its Constitutional monopoly on war-making powers more than half a century ago.

Nonetheless, Obama was rightly criticized for flouting the Constitution in his Libya intervention. Trump is hurrying us further down that slippery slope. Once American presidents quit paying lip service to needing either Congressional approval or international sanction before blowing any spot on the map to kingdom come, our already unlovely role as the world’s policeman is bound to start looking increasingly undistinguishable from unbridled gangsterism. Figleaves are useful things sometimes.

Until last Tuesday, Trump plainly hadn’t thought twice about the Syrian people’s sufferings. Otherwise, he wouldn’t have happily demonized refugees from that wretched country as potential terrorists. (At least so far, he hasn’t changed his tune on that, either.) If the news’ images of dead and dying men, women and especially children in Idlib Province shocked him—and he did sound genuinely shaken when he described his reaction—that suggests an untapped streak of decency few of Trump’s critics would give him credit for.

But it also means he’s an obtuse ignoramus, because Syria has been a hellscape for six years now and he should have familiarized himself with its horrors long ago. Besides, if he can pull a complete 180 like this on the spur of the moment, it’s not a reassuring guide to his future behavior, when he could be motivated to similarly drastic steps by petulance or rage instead of moral revulsion.

Remember, only a week ago, Secretary of State Rex Tillerson was blandly declaring that “the longer-term status of President Assad will be decided by the Syrian people,” essentially disavowing any U.S. interest in deposing Assad or getting further embroiled in the conflict. Marco Rubio, among others, believes Tillerson’s statement was Assad’s green light to advertise his ruthlessness (again) by launching Tuesday’s chemical attack. Now, though, the phlegmatic Tillerson is supposedly organizing a, yes, coalition to oust Assad from power on his boss’s orders. Who’s to say Trump won’t change his mind again by mid-April and decide Assad is just the strong man Syria needs?

Trump is also contemplating further military action, presumably no longer confined to punitive air strikes. Whatever his ostentible justification will be, let’s recall that his poll ratings are in the toilet, Russiagate is dogging him, his legislative agenda is D.O.A. and he’d love to distract us from those nuisances. Ever since his inaugural, people have been speculating about how soon and where he’ll start a war to put his domestic troubles behind him. This may be it.

Because Assad is a despot who’s murdered thousands of his own people by heinous means, no one would weep if the world was rid of him, just as nobody wept when Saddam Hussein and Muammar Gaddafi went down. But as was the case in Iraq and Libya, only more so, there’s no aftermath in sight worth rooting for. The country is already so destroyed that either Assad or his replacement will be ruling a virtual wilderness.

That makes it hard to justify expending a single American life on the project, especially if you want to be hard-headed and ask what we’d actually gain. In humanitarian terms, the U.S. would do better to welcome our share of the war’s estimated five million refugees instead of shunning them. But we all know that’s exactly what Trump won’t do.

Trump isn’t exactly a specialist in locating safe middle grounds.

Within Syria, there’s essentially no faction we can responsibly back save for the tricky but narrowly focused purpose of defeating ISIS, which was the extent of our involvement there until this week. By now, just keeping a handle on who’s fighting whom makes the average vat of spaghetti look like a Mondrian painting.

Backed by Russia, Iran and Hezbollah, Assad is battling both ISIS (sort of) and a variety of rebel groups to retain power. While making sure to keep daylight between ourselves and Assad, the U.S. supports local militias against ISIS, which may amount to sowing dragon’s teeth so far as those groups’ future friendliness to us is concerned. Turkey claims to be opposed to both Assad and ISIS, but has been accused of colluding with the latter when it’s convenient. And so on.

That’s the conflict Trump has impetuously ratcheted up America’s stake in, with no clear goal beyond his sudden (and possibly temporary) aversion to Assad’s regime. The risks are multiple, but the primary one is a clash—accidental or otherwise—with the 4,000 Russian military personnel deployed in Syria.

Though nobody in the Russian contingent stationed at the air base hit by our Tomahawks was harmed, Russian Prime Minister Dmitry Medvedev said the attack “came within an inch” of provoking hostilities. Vladimir Putin has already suspended the agreement between the U.S. and Russia that kept our planes and theirs from tangling in Syrian airspace. He’s also announced plans to help Assad beef up his anti-aircraft defenses, meanwhile sending a Russian frigate steaming straight toward where our Navy launched yesterday’s strikes.

Here’s where the true incoherence of Trump’s abrupt turnaround on Syria hits home. Maybe he’s fed up with being called Putin’s puppet; who wouldn’t be, except Medvedev? But an actual armed confrontation with Russia in the world’s most volatile and crowded trouble spot seems like an awfully extreme way of disproving the charge.

As we all know, however, Trump isn’t exactly a specialist in locating safe middle grounds. Perhaps what ought to chill his compatriots most right now is the memory that, at one of his first foreign-policy briefings during the 2016 campaign, he allegedly kept badgering the nameless official briefing him to explain why we couldn’t just use our nukes whenever a crisis erupted. Now he’s got the codes.