President Donald Trump’s decision to withdraw all US troops from Syria has been met with strong criticism.
Mr Trump made the announcement on Wednesday, asserting that the Islamic State (IS) group had been defeated.
But major allies, including senior Republicans and foreign powers, have disputed the claim and say the move could lead to a resurgence of IS.
US troops have helped rid much of Syria’s north-east of the jihadist group, but pockets of fighters remain.
Republican Senator Lindsey Graham, who is one of Mr Trump’s supporters, called the withdrawal decision a “huge Obama-like mistake”.
Senator Graham, who sits on the armed services committee, warned that the withdrawal would have “devastating consequences” both in Syria and beyond.
He said that he feared it would mean ceding influence in the region to Russia and Iran.
“An American withdrawal at this time would be a big win for ISIS [IS], Iran, Bashar al-Assad of Syria, and Russia,” he said in a statement.
The Pentagon said it was transitioning to the “next phase of the campaign” to eliminate IS but did not provide further details.
President Trump, who has long promised to pull American troops out of Syria, said on Twitter that it was time to bring them home after their “historic victories”.
The White House would not give a timescale for the withdrawal but defence officials quoted by the New York Times said President Trump wanted it done within 30 days.
Meanwhile, the UK government distanced itself from President Trump’s assertion that IS had now been defeated.
A Kurdish-led alliance in Syria says President Trump’s surprise decision to withdraw US troops will allow the IS group to recover.
A statement from the Syrian Democratic Forces (SDF) warned of a military vacuum that would leave the alliance trapped between hostile parties.