We now know how many cruise missiles it takes to turn you from pariah to respected member of the American foreign policy establishment: 59 — the number President Trump fired on a Syrian government airfield on Thursday. “I think Donald Trump became president of the United States,” the CNN host Fareed Zakaria gushed.

And yet firing missiles at half-empty air bases does not make up for a lack of foreign policy acumen, let alone a strategy for dealing with a Middle East that has consumed American blood and treasure for at least 15 years. In fact, the good money says that Mr. Trump is, through plan or happenstance, likely to push us further into the fighting, whatever he promised on the campaign trail.

In the coming weeks, we’ll have a long debate over where America is headed in the Middle East. But the question that historians will ask, decades from now, is how those 15 years of flailing failed to teach us anything.

“All wars are fought twice, the first time on the battlefield, the second time in memory,” wrote the novelist Viet Thanh Nguyen. Americans understood Vietnam to be a grievous defeat that required fresh thinking. In the 1970s, they set out on a long reckoning with its consequences, pioneering the promotion of human rights and asserting congressional control over war powers.