ABOARD A MILITARY AIRCRAFT — Defense Secretary Jim Mattis on Friday said the United States would change its military footprint in Syria, as the Islamic State loses ground.

“As you have observed in Syria, the enemy is collapsing—in many cases faster than many people in the media forecasted,” he said. “That fighting is now dropping off, in terms of the need for offensive capability.”

“Consistent with that we’re changing the composition of forces to something that supports the diplomats and the Geneva process,” he said, referring to a United Nations-brokered peace process.

“We’re going from a military-led effort there to … a diplomatically led effort now,” he said.

He noted this week’s announcement that a U.S. Marine artillery unit with 400 Marines was heading home. It is not clear what the current number of U.S. forces are in Syria, but on September 30, there were 1,720 active and reserve forces, according to Pentagon statistics.

Mattis also signaled a reduction in support for the Syrian Kurdish forces, known as the YPG. The U.S.-led military coalition worked with and supplied the YPG with arms to retake ISIS’s stronghold in Syria of Raqqa this year.

“The YPG is armed, and as the coalition stops offensive [operations], then, obviously, you don’t need that, you need security—you need police forces. That’s local forces,” he said.

Asked whether the U.S. would stop providing arms to the Kurds, Mattis responded, “We’re going to go exactly along the lines of what the president announced.”

President Trump previewed that decision last week during a phone call with Turkish President Recep Tayyip Erdogan.

“Consistent with our previous policy, President Trump also informed President Erdogan of pending adjustments to the military support provided to our partners on the ground in Syria, now that the battle of Raqqa is complete and we are progressing into a stabilization phase to ensure that ISIS cannot return,” a White House readout of a November 24 phone call between Trump and Erdogan read.

Turkey has been upset by the U.S. supplying arms to the YPG, which it considers an affiliate of the terrorist group PKK that is advocating for a breakaway state from Turkey.