The U.S. military is preparing to withdraw its forces from Syria, people familiar with the matter said Wednesday, a move that marks an abrupt reversal of the American military strategy in the Middle East. U.S. officials began informing partners in northeastern Syria of their plans to begin an immediate pullout of American forces from the region where they have been trying to wrap up the campaign against Islamic State, the people said. “The Pentagon has an order to move troops out of Syria as quickly as possible,” a U.S. official said. U.S. military officials have refused to say what a withdrawal timeline could look like. The White House didn’t immediately respond to a request for comment on the move. But President Trump wrote on Twitter Wednesday morning that “We have defeated ISIS in Syria, my only reason for being there during the Trump Presidency.”

The move follows a call last week between Mr. Trump and Turkish President Recep Tayyip Erdogan, who has threatened to launch an assault on America’s Kurdish partners in Syria.

Officially, the U.S. military has no authority to battle Iran in Syria. Their mission has been to defeat Islamic State and ensure the militant group that once controlled large swaths of Syria and Iraq is unable to regroup. That task is largely complete.

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