President Donald Trump has told the UK and other European allies to take back and put on trial more than 800 Islamic State (IS) fighters captured in the final battle against the group.
His tweet comes as US-backed Kurdish forces continue an assault on the last pocket of IS territory on the Syrian side of the Iraqi border, at Baghuz.
The captured IS fighters are being held by the Kurdish-led forces.
Mr Trump has said for several days that the IS caliphate is “ready to fall”.
What is Mr Trump’s reasoning on IS fighters?
He said in a tweet: “The US does not want to watch as these ISIS fighters permeate Europe, which is where they are expected to go. We do so much, and spend so much – Time for others to step up and do the job that they are so capable of doing.”
Otherwise, he said, the US would be forced to release them
iya Furat, the leader of the battle for Baghuz for the SDF, said IS fighters were now trapped in a section of the town that was 700 metres long and wide.
On Sunday, SDF spokesman Mustefa Bali said the IS group had blocked roads out of zone, stopping some 2,000 civilians there from escaping.
Thousands have left the Baghuz pocket in recent weeks but one SDF fighter told Agence France-Presse it had been two days since anyone had arrived, with lorries parked to transport them lying empty.
A spokesman for the US-led coalition, Sean Ryan said those who had escaped reported that remaining civilians were being used as human shields.
IS has suffered substantial losses, but the UN has said it still reportedly controls between 14,000 and 18,000 militants in Iraq and Syria.