The United States has started bringing home troops from Syria as it moves to a new phase in the campaign against the Islamic State (IS) extremist group, the White House says.
The militant's "territorial caliphate" had been defeated, White House spokeswoman Sarah Sanders said in a statement on December 19, amid media reports saying that the United States was preparing to withdraw all its troops from Syria.
"These victories over [the IS group] in Syria do not signal the end of the Global Coalition or its campaign. We have started returning United States troops home as we transition to the next phase of this campaign," Sanders said.
Earlier, President Donald Trump tweeted the IS group had been defeated in Syria and that was his "only reason for being there."
There are currently around 2,000 American troops in Syria, many of them special operations forces working with an alliance of Kurdish and Arab militias battling the IS group.
Most U.S. soldiers are based in northeastern Syria, where they had been helping to rid the area of IS fighters, but pockets of militants still remain.
CNN quoted a defense official as saying on December 19 that the planning was for a "full" and "rapid" pullout.
And CBS said it was told that the White House ordered the Pentagon to "begin planning for an immediate withdrawal."
The coalition has "liberated" the IS-held territory, but the campaign against the group "is not over," Pentagon spokeswoman Dana White said.
"For force protection and operational security reasons we will not provide further details. We will continue working with our partners and allies to defeat ISIS wherever it operates," White said in a statement, using an acronym for Islamic State.
The Russian Foreign Ministry said the decision to withdraw U.S. troops from Syria creates prospects for a political settlement of the conflict there, according to the TASS news agency.
Russia has repeatedly asserted that U.S. forces have no right to be in Syria because Syrian President Bashar al-Assad's government has not approved their presence.
Republican Senator Lindsey Graham said a decision by Trump to withdraw troops from Syria at this time would be "a mistake" and a “big win” for the IS group, Assad, and its allies -- Russia and Iran.
Both Moscow and Tehran have given Assad crucial support throughout the Syrian conflict, which began with a government crackdown on protesters in March 2011 and has left more than 400,000 people dead, displaced millions, and devastated many historical sites across the country.
In 2014, IS fighters seized large swaths of Syrian and Iraqi territory in a lightning offensive and proclaimed a so-called Islamic "caliphate."
IS militants have lost virtually all the territory they once controlled in Iraq, but still carry out sporadic attacks.