US military to keep around 200 troops in Syria after pullout

The US military will keep around 200 troops in Syria after President Donald Trump's pullout from the war-torn country, the White House said on Thursday.

"A small peace-keeping group of about 200 will remain in Syria for a period of time," White House spokeswoman Sarah Sanders said.

The announcement comes amid fierce criticism of Trump's decision to withdraw America's 2,000 or so troops from Syria by April 30, with members of his own Republican Party blasting the move.

In December, Trump declared victory over the Islamic State group in Syria, even though thousands of extremists remain and fighting continues around their last holdout.

Sanders did not provide additional details, but the troops' "peace-keeping" designation could pave the way for European allies to commit forces for such a mission.

Acting Defence Secretary Patrick Shanahan visited Europe last week where he attempted to convince allies to maintain a troop presence in Syria after the US pulls out. But he struggled to persuade other countries why they should risk their forces with America gone.

Politicians grilled Shanahan on Trump's contentious decision on the sidelines of the Munich Security Conference last weekend. Many in Trump's own Republican Party have questioned the wisdom of the move.

According to The Washington Post, Republican Senator Lindsey Graham, the leader of a delegation of lawmakers who had gone to Munich, asked Shanahan if he had told European allies that the US troop presence would be zero by April 30.

"Yes, that's been our direction," Shanahan reportedly said.

"That's the dumbest F***ing idea I've ever heard," Graham told the Post he had responded. 

A US official told AFP that Graham's outrage was aimed more at Trump's withdrawal plans than it was at Shanahan himself. Graham reportedly described a number of possible outcomes for a precipitous US withdrawal, including a Turkish attack on US-backed Kurdish forces and a resurgence of IS.

"If the policy is going to be that we are leaving by April 30, I am now your adversary, not your friend," Graham reportedly told Shanahan. 

Also, earlier on Thursday Trump spoke with Turkish President Recep Erdogan, and the two men discussed Syria, according to a White House summary.

"The two presidents agreed to continue coordinating on the creation of a potential safe zone" in Syria, the readout said.

At the height of its rule, IS imposed its brutal ideology on a territory roughly the size of the United Kingdom, attracting thousands of supporters from abroad.

But the extremists have since lost almost all their territory save for a tiny sliver of around half a square kilometre (a fifth of a square mile) in the eastern Syrian village of Baghouz.

The US-backed Syrian Democratic Forces (SDF) are working towards evacuating civilians remaining in the holdout, so they can polish off the dying IS "caliphate" whether through an assault or a surrender deal.

Syria's Kurds have long demanded the repatriation of foreigners accused of belonging to IS in their custody, but their home countries have been reluctant.