"We have defeated ISIL in Syria," said US President Donald Trump.
ADVERTISEMENTThe United States has begun withdrawing its forces from Syria, according to reports.
All US State Department personnel are being evacuated from Syria within 24 hours, an official told Reuters.
That comes after the White House said it had started withdrawing US forces from the country.
The official said US plans to pull military forces out of the country once the final stages of the last operation against so-called Islamic State (ISIL) were complete.
The time-frame for the troop pullout is expected to be between 60 and 100 days.
The decision came after a phone call between US President Donald Trump and his Turkish counterpart Tayyip Erdogan on Friday.
"Everything that has followed is implementing the agreement that was made in that call," the official said.
"We have started returning United States troops home as we transition to the next phase of this campaign," White House spokeswoman Sarah Sanders said in a statement.
The Pentagon said it had started the process of returning U.S. troops from Syria as the United States began to transition into the next phase of the campaign.
"The Coalition has liberated the ISIS-held territory, but the campaign against ISIS is not over," Pentagon spokeswoman Dana White said in a statement. "We have started the process of returning U.S. troops home from Syria as we transition to the next phase of the campaign," she said.
US President Donald Trump said the US had defeated ISIL in Syria, adding that it was the only reason he had kept troops in the country.
Trump has previously expressed a strong desire to bring troops home from Syria when possible.
A British defence minister responded to Trump's tweet and said the US president is wrong to claim that Islamic State has been defeated in Syria.
A US decision to pull forces out of Syria would upend assumptions about a longer-term American military presence in Syria, which Defense Secretary Jim Mattis and other senior US officials had advocated to help ensure Islamic State cannot reemerge.
The United States still has about 2,000 troops in Syria, many of them special operations forces working closely with an alliance of Kurdish and Arab militias known as the Syrian Democratic Forces, or SDF.
A complete withdrawal of US troops from Syria would still leave a sizeable American military presence in the region, including about 5,200 troops across the border in Iraq.
Much of the US campaign in Syria has been waged by warplanes flying out of Qatar and other locations in the Middle East.
Syria's civil war has killed hundreds of thousands of people and displaced around half of Syria's pre-war population of about 22 million.
ADVERTISEMENTBrett McGurk, the US special envoy for the global coalition to defeat ISIL, said last week that the group was down to its last 1% of the territory it once held in its self-styled "caliphate." The group has no remaining territory in Iraq.
"Even as the end of the physical caliphate is clearly now coming into sight, the end of ISIS will be a much more long-term initiative," McGurk told a State Department briefing on December 11.
A US withdrawal could open Trump up to criticism if Islamic State reemerged.
Trump has previously lambasted his predecessor, Barack Obama, for the withdrawal of U.S. forces from Iraq that preceded an unravelling of the Iraqi armed forces. Iraqi forces collapsed in the face of Islamic State's advance into the country in 2014.