Trump Wants to Put America First. He Has No Idea How.

Donald Trump ran on peace. Soon he bombed the Middle East. The year was 2025 — and 2017. Back then, just months into his first term, Mr. Trump launched cruise missiles into a Syrian-government airfield, putting a temporary halt to a chorus of warnings that Mr. Trump was some sort of isolationist, out to withdraw the United States from world affairs.

At the start of Mr. Trump’s second term, history didn’t merely repeat; it doubled down. This time, the president evinced greater determination to be a “peacemaker and unifier,” as he put it. Once again, the guardians of foreign policy orthodoxy in Washington fretted that he might dismantle their project. For the same reason, advocates of less American military intervention in the world, myself included, held out a bit of hope.

Perhaps our eyes deceived us, but there was Mr. Trump diving into talks to stop the carnage in Ukraine and Gaza and seeking a diplomatic deal with Iran. The president even sounded curiously flexible toward China, his first-term bête noire. “We will measure our success,” Mr. Trump announced in his Inaugural Address, “not only by the battles we win but also by the wars that we end — and perhaps most importantly, the wars we never get into.”

This is a laudatory standard, which Mr. Trump deserves credit for setting. But six months into his presidency, he deserves more blame for failing to meet it. He has delivered no peace, whether in Europe or in the Middle East. His strike on Iran sums up his struggles: a frantic, fumbling attempt at negotiation cut short by a risky attack that sets the stage for further war.

Inartful dealings are only half the trouble. Mr. Trump is a thoroughly situational man in a deeply structural bind. Year after year, the United States stations its military forces on geopolitical fault lines in Europe, Asia and the Middle East simultaneously. And year after year, it gets exactly what it has placed itself to receive, inheriting distant conflicts as its own and lurching from crisis to crisis at times of its many adversaries’ choosing. If Mr. Trump is to reduce the country’s exorbitant defense burdens, as he claims to want, he must take the United States out of the position that guarantees them.

But for all of Mr. Trump’s talk, and his critics’ fears, it remains uncertain whether he will even really try.