Erdogan’s ambitions go beyond Syria. He says he wants nuclear weapons.

It was not the first time Mr. Erdogan has spoken about breaking free of the restrictions on countries that have signed the Nuclear Nonproliferation Treaty, and no one is quite sure of his true intentions. The Turkish autocrat is a master of keeping allies and adversaries off balance, as President Trump discovered in the past two weeks.

“The Turks have said for years that they will follow what Iran does,” said John J. Hamre, a former deputy secretary of defense who now runs the Center for Strategic and International Studies in Washington. “But this time is different. Erdogan has just facilitated America’s retreat from the region.”

“Maybe, like the Iranians, he needs to show that he is on the two-yard line, that he could get a weapon at any moment,” Mr. Hamre said.