nytimes.com | By Eric Scmitt | April 3, 2019

WASHINGTON — Now that the Islamic State has been driven from its last sliver of territory in Syria, hundreds of American troops — not just their equipment — are leaving the war zone, just as President Trump ordered in December.

But in the latest twist to the on-again, off-again American withdrawal, the Pentagon plans to cut its combat force in northeastern Syria roughly in half by early May, or to about 1,000 troops, and then pause, American officials said on Friday.

The military will then assess conditions on the ground and reduce the number of forces every six months or so, until it reaches the 400 troops in Syria that Mr. Trump approved in February. They will include 200 in a multinational force in the northeast and another 200 at a small outpost in southeastern Syria, where they will seek to counter Iran’s influence throughout the country.

The pause is another important shift from Mr. Trump’s initial order to pull out all 2,000 American troops from Syria immediately, and has not been previously reported.

Commanders and Pentagon officials had said in February that they would most likely have to draw down to the smaller residual force by late April or early May. But under the latest plans, the Pentagon may not have to reach that lowest troop level until the fall of 2020, said the officials, who discussed the sensitive strategy on condition of anonymity.

The longer timetable would give the Trump administration more time to negotiate with European allies who had said they would not leave troops in Syria if the United States withdrew all its forces.

It also would allow more time for Washington to work out details of a safe zone south of the Turkish border. The area is still vulnerable to both a resurgence of the Islamic State and an incursion by troops from Turkey, which wants to make sure Kurdish fighters cannot launch terrorist attacks across its border.

Military officials cautioned on Friday that the withdrawal timetable remained fluid and that final force levels were subject to change given a range of factors, from allied troop contributions to new directions from Mr. Trump.

Col. Patrick Ryder, a spokesman for the military’s Joint Chiefs of Staff, declined to comment on specific withdrawal plans.

“We continue to implement the president’s direction to draw down U.S. forces to a residual presence in a deliberate and coordinated manner,” Colonel Ryder said in an email. “This work is ongoing and, for operational security reasons, we will not discuss specific U.S. troop numbers or drawdown timelines.”

The American military started withdrawing equipment from Syria in January, just weeks after Mr. Trump’s order to wind down operations. But the number of troops actually increased to around 3,000 in February to help protect the final process of pulling out.

Officials said it has only been in recent days that the current number of American troops fell below the level of the slightly over 2,000 personnel who were in Syria when Mr. Trump issued his order in December.

“Armed forces are being withdrawn,” James F. Jeffrey, the American special envoy for Syria, told reporters on Monday. “We had to reinforce initially to bring in more combat power, and now we’re going back down toward what the final number will be.”

Mr. Jeffrey and other United States officials warned that even before an American-backed Kurdish and Arab militia ousted the last extremist fighters from the eastern Syrian village of Baghuz last Saturday, the Islamic State had already reverted to its insurgents roots — carrying out guerrilla attacks, bombings and assassinations.

“This is not the end of the fight against ISIS,” Mr. Jeffrey said, using another name for the Islamic State. “That will go on, but it will be a different kind of fight.”

“The fight is fresh in Syria, and ISIS elements are in shock from having lost this terrain,” Mr. Jeffrey added. “In Iraq, they’ve had more time to reconstitute. But again, they’re reconstituting in small groups operating in the shadows as a low-level insurgency. They’re not holding terrain, they’re not controlling populations.”

The American-led military command in Baghdad said in a statement on Friday that allied and Iraqi security forces had carried out air and ground operations against pockets of Islamic State fighters just across the Syria border in northern and western Iraq this week.

And American commandos continue to hunt Abu Bakr al-Baghdadi, the elusive Islamic State leader who is believed to be hiding in the area along the Iraq-Syria border or the Sunni-dominated region of western Iraq. “Finding the top leadership of ISIS or other terrorist groups is always a priority,” Mr. Jeffrey said.

In another sign of the open-ended mission, the Defense Department has requested $300 million in its proposed budget for fiscal 2020 — the same amount as a year ago — to continue supporting the Kurdish-led militia called the Syrian Democratic Forces, according to Lt. Cmdr. Rebecca Rebarich, a Pentagon spokeswoman. The militia has been the primary ground force combating the Islamic State in Syria.

The Pentagon largely intends to use the money to pay militia forces that will continue to carry out mop-up operations against hundreds or even thousands of Islamic State fighters who remain at large or who have formed sleeper cells in the Middle Euphrates River Valley, officials said.

The remaining American forces will also continue to train the Kurdish and Arab militia.

Gen. Joseph F. Dunford Jr., the chairman of the Joint Chiefs of Staff, told Congress in testimony this week that the residual force would “continue to train, advise, assist for our Kurdish partners on the ground.”

Mr. Jeffrey noted other priorities for the administration in Syria now that offensive actions against the Islamic State have wound down: humanitarian, reconstruction and stability operations. So far, the international coalition has provided $325 million for postconflict stability and reconstruction efforts in northeastern Syria, he said.

Administration officials say they are also working with Turkey on a so-called safe zone in an area just south of the Turkish border in northeastern Syria. “We’re working for a solution that will meet everybody’s needs,” Mr. Jeffrey said.