In one sense, the Syria debacle is a singular moment in the Trump presidency, and arguably in American history. I can’t think of another momentous decision by a commander in chief that was instantly recognizable as a disaster for which the president was entirely to blame.

Even if you think the Iraq war was a catastrophic blunder, it wasn’t immediately and universally recognizable as such. And President Bush could point to support from both parties in Congress, his advisers, the intelligence community and even his predecessor. The Bay of Pigs was backed by the Pentagon and CIA. The Gulf of Tonkin Resolution passed Congress, unanimously in the House and 88-2 in the Senate.

But here the cheese stands alone.

And yet, in another sense, this all feels so familiar. How many times has Mr. Trump made a glandular, impulsive decision without heed to the facts, consequences or the advice of his own hand-picked advisers? Then, when criticism mounts, he and his defenders grab a sloppy paint pot of ideological buzzwords and campaign slogans in an attempt to camouflage the move as part of some grand theoretical framework or electoral mandate.

Mr. Trump and the handful of surrogates willing to defend this grotesquerie are quite comfortable arguing about “endless wars” and “Trump’s mandate” as an abstract matter. I think they’re wrong in nearly every particular. But even engaging in debate on those terms is a gift to the president.

Talk of “realism,” “America First” and “endless war” is a rhetorical safe harbor that works well on Twitter and cable news because it gives the impression that this is a serious conflict of philosophical perspectives. Even if you agree with all of that stuff, the fact remains that this was a scandalously incompetent and reckless action. Fighting about the “policy” lets Mr. Trump off the hook for the bungled implementation. It’s like Democrats defending the botched Bay of Pigs operation by invoking the Monroe Doctrine.

Mr. Trump may indeed have campaigned on getting out of Syria. He didn’t campaign on potentially freeing thousands of Islamic State fighters, greenlighting ethnic cleansing or empowering Syrian President Bashar Assad and Russian President Vladimir Putin.

A serious policy of disengagement from the Middle East would require working with our allies in the region and elsewhere. It would involve intense planning by the Pentagon and State Department. And, most importantly, it would necessitate tough negotiations with the Turks to minimize our betrayal of a people who lost some 11,000 troops fighting at our side.

Mr. Trump went a different way. According to reporting by Jennifer Griffin of Fox News — not normally a target of Mr. Trump’s “fake news” broadsides — Mr. Trump “went off script from what his national [security] team gave him as talking points for his phone conversation with the Turkish president.”

In an instant, Mr. Trump blew up months of negotiations with Turkey to establish a Kurdish safe zone that would satisfy both Turkey’s concerns and make sure that Islamic State wasn’t given a lifeline.

Whether Mr. Trump was trying to ingratiate himself with Mr. Erdogan — he does like strongmen — or was intimidated by the Turkish despot remains unknown. Either way, in a phone call, he in effect encouraged Mr. Erdogan to go for it. Within days, the Turks rolled across the border. Arab militias began the initial stages of what could turn into ethnic cleansing. When the Kurds begged for air cover, Mr. Trump ordered our planes to stay on the tarmac. Already, there are videos authenticated by U.S. officials of roadside executions of Kurds. The Turks have even rained artillery around an American outpost, requiring a full U.S. retreat from northern Syria and forcing Kurdish forces to ally themselves with the Syrian government. On Thursday, Vice President Mike Pence announced that he had negotiated a five-day suspension of Turkey’s operations in Syria, but much damage has already been done, and more is likely to follow.

Mr. Trump had claimed after the call that Mr. Erdogan promised to take responsibility for guarding Islamic State prisoners. The Turkish government quickly announced there was no such commitment. The Turks might be lying, though Mr. Trump’s silence suggests they aren’t. Either way, they put one over on the self-proclaimed world’s greatest negotiator.

The cycle wouldn’t be complete without Mr. Trump doing his best to humiliate his defenders, desperately trying to squeeze square facts into the round holes of some theory. The same week he said we must disengage from the Middle East and its conflicts, he sent thousands more American troops to Saudi Arabia. He said he opposed Turkey’s incursion, but he instructed his United Nations ambassador to vote with Russia to block condemnation of it. He’d said the Turks were making a mistake, but tweeted, “Let them” fight. And he approved sanctions on Turkey for the “destabilizing actions in northeast Syria” he greenlit. He might as well put the sanctions on himself.

These events aren’t the result of a serious policy of American withdrawal from “endless wars,” they’re the inevitable and familiar byproduct of a president simply winging it.

Jonah Goldberg is editor-in-chief of The Dispatch and the host of The Remnant podcast. His Twitter handle is @JonahDispatch.