Donald Trump is pulling all 2,000 US troops out of Syria, officials announced Wednesday, as the president suddenly declared victory over the Islamic State.
He was contradicting his own experts’ assessments and sparked surprise and outrage from members of his party, who called his action rash and dangerous.
The US began airstrikes in Syria in 2014, and ground troops moved in the following year to battle the Islamic State, or Isis, and train Syrian rebels in a country torn apart by civil war.
Mr Trump abruptly declared their mission accomplished in a tweet.
On Wednesday, as Vice President Mike Pence met top military leaders in the Pentagon, Mr Trump tweeted: “We have defeated ISIS in Syria, my only reason for being there during the Trump Presidency.”
Later, Mr Trump posted a video on Twitter in which he said it was “heartbreaking” to have to write letters and make calls to the loved ones of those killed in battle.
“Now it’s time for our troops to come back home,” he said.
His declaration of victory is far from unanimous.
The decision will fulfil Mr Trump’s long-stated goal of bringing troops home from Syria, but military leaders argue that Islamic State remains a threat and could regroup as it battles in Syria’s long-running civil war.
Mr Trump has argued for the withdrawal since he was a presidential candidate.
But the decision underscores the division between him and his military advisers, who have said in recent weeks that pockets of IS militants remain and US policy has been to keep troops in place until the extremists are eradicated.
Israeli Prime Minister Benjamin Netanyahu, who remains concerned about Iranian efforts in the area, reacted in non-committal fashion after talking with Mr Trump by telephone.
“This is, of course, an American decision,” he said.
Israel will learn of the timetable and manner of withdrawal, he said, and no matter what “we will safeguard the security of Israel and protect ourselves from this arena”.
Leading Republican senators reacted with displeasure to the news.
Senator Lindsey Graham, typically a Trump backer, said he was “blindsided” by the report and called the decision “a disaster in the making”.
He said: “The biggest winners in this are ISIS and Iran.”
Marco Rubio of Florida said the withdrawal would be a “grave error with broader implications” beyond the fight against IS.
Just last week, the US special envoy to the anti-Isis coalition, Brett McGurk, said US troops would remain in Syria even after Islamic State was driven from its strongholds.
“I think it’s fair to say Americans will remain on the ground after the physical defeat of the caliphate, until we have the pieces in place to ensure that that defeat is enduring,” Mr McGurk told reporters on December 11.
“Nobody is declaring a mission accomplished. Defeating a physical caliphate is one phase of a much longer-term campaign.”
And two weeks ago General Joseph Dunford, chairman of the Joint Chiefs of Staff, said the US still has a long way to go in training local Syrian forces to prevent a resurgence of IS and stabilise the country.
He said it will take 35,000 to 40,000 local troops in north-eastern Syria to maintain security over the long term, but only about 20% of them have been trained.
Mr Trump’s national security adviser, John Bolton, said in September that the US would keep a military presence in Syria as long as Iran is active there.
“We’re not going to leave as long as Iranian troops are outside Iranian borders and that includes Iranian proxies and militias,” he said.
James Stavridis, a former Navy admiral who served as top Nato commander, tweeted Wednesday that “Pulling troops out of Syria in an ongoing fight is a big mistake. Like walking away from a forest fire that is still smoldering underfoot. Big winner is Iran, then Russia, than Assad. Wrong move.”
The withdrawal decision, however, is likely to be viewed positively by US ally Turkey, and comes following several conversations between Mr Trump and Turkish President Recep Tayyip Erdogan over the past weeks.
The Turks have targeted US-backed Kurdish troops along the Syria-Turkey border, which Turkey considers an insurgent threat.
A US withdrawal – including the end of joint US and Turkish patrols along the border – could open the door for more Turkish operations against the Syrian rebels.
Just hours before the withdrawal decision became public, the State Department announced late Tuesday that it had approved the sale of a 3.5 billion dollar (£2.7 billion) Patriot missile defence system to Turkey.
The US first launched airstrikes against IS fighters in Syria in 2014. In the years that followed, the US began partnering with Syrian ground forces to fight the extremists.
The Pentagon recently said that IS now controls just 1% of the territory it originally held.