Mr. Sadjadpour called the speech “strategically incoherent.” But that can be said about much of Mr. Trump’s Middle East policy in the past few months. The president pulled a small, fairly safe American force out of Syria that was primarily engaged in fighting the Islamic State with Syrian Kurdish allies, claiming it was time to halt “endless wars.” He decided not to respond when Iran first shot down an unmanned American drone and then executed a precision attack on Saudi oil facilities, leaving the impression inside the Islamic Revolutionary Guards Corps that America’s Middle East ally was not worth defending.

And then, surprising everyone, including his own military advisers, he ordered the targeted killing of Maj. Gen. Qassim Suleimani, Iran’s most important commander, saying that he was planning attacks on American targets, although the administration has offered few details.

Already that decision has led to a host of unintended consequences, including the sending of thousands more United States troops to the Middle East to defend American assets and interests that Mr. Trump only a few months ago suggested are not worth defending.

His answer to that contradiction seems to be to ask NATO to do the job. Presumably he wants allied forces to patrol the Persian Gulf at a time that tanker companies are halting their shipments across the Strait of Hormuz and airlines are avoiding Iraqi and Iranian airspace.

It seems unlikely they will heed his call. NATO’s leading members argue that it was Mr. Trump who picked this fight with Iran, by dumping the 2015 nuclear deal reached during the Obama administration that, in their mind, was working. And, as Mr. Trump himself complains, they do not have the military capability to play the role the United States has played.

“His failure to consult the allies or take their interests into consideration will make it extremely difficult to get their support,” said R. Nicholas Burns, the former American ambassador to NATO during the early days of the Afghanistan war, when Europe did come to America’s aid. “Very few of the allies trust him and will not follow blindly the most anti-NATO president in seven decades.”

The Iranians are betting on exactly that. Their strategy has been to peel Europe, China and Russia — the other nations involved in negotiating the accord — away from the United States. For a long while, they succeeded as European powers kept devising complex plans to counteract American sanctions on Iran.