Rather than self-defense, the Suleimani killing seems like the dreadful result of several intersecting dynamics. There’s the influence of rapture-mad Iran hawks like Pompeo and Vice President Mike Pence. Defense officials who might have stood up to Trump have all left the administration. According to Peter Bergen’s book “Trump and His Generals,” James Mattis, Trump’s former secretary of defense, instructed his subordinates not to provide the president with options for a military showdown with Iran. But with Mattis gone, military officials, The Times reported, presented Trump with the possibility of killing Suleimani as the “most extreme” option on a menu of choices, and were “flabbergasted” when he picked it.

Trump likely had mixed motives. He was reportedly upset over TV images of militia supporters storming the American Embassy in Iraq. According to The Post, he also was frustrated by “negative coverage” of his decision last year to order and then call off strikes on Iran.

Beyond that, Trump, now impeached and facing trial in the Senate, has laid out his rationale over years of tweets. The president is a master of projection, and his accusations against others are a decent guide to how he himself will behave. He told us, over and over again, that he believed Barack Obama would start a war with Iran to “save face” and because his “poll numbers are in a tailspin” and he needed to “get re-elected.” To Trump, a wag-the-dog war with Iran evidently seemed like a natural move for a president in trouble.

It’s hard to see how this ends without disaster. Defenders of Trump’s move have suggested that he might have re-established deterrence against Iran, frightening its leadership into restraint. But Vali Nasr, a Middle East scholar at Johns Hopkins University and former senior adviser to Obama’s State Department, tells me that Iran likely believes that it has to re-establish deterrence against the United States.

“If they don’t do anything, or if they don’t do enough, then Trump will get comfortable with this kind of behavior, and that worries them,” said Nasr. To Iranians, after all, America is the aggressor, scrapping a nuclear agreement that they were abiding by and imposing a punishing “maximum pressure” sanctions campaign. Just like militarists in the United States, they’re likely to assume that weakness invites attacks. “I don’t think they want to provoke war, but they do want to send a signal that they’re prepared for it,” said Nasr.