Loading The decision drew bipartisan criticism from US lawmakers who said it leaves Syria's future in the hands of Moscow and Tehran, allies of President Bashar al-Assad whose intervention in the conflict averted his potential defeat in a conflict that started more than seven years ago. "This is chaos," said Republican Senator Lindsey Graham, who said earlier on Twitter that the move would be a "boost to ISIS" and a "huge Obama-like mistake." Graham, who has served as a key adviser to Trump and plays golf with him frequently, said he'd be meeting Defence Secretary Jim Mattis later in the day to try and understand the situation. Mattis discussed the potential withdrawal with Trump a week ago, according to one official who declined to say how the defence chief reacted.

In a video posted on Twitter later on Wednesday, Trump said, "I get very saddened when I have to write letters or call parents or wives or husbands of soldiers who have been killed fighting for our country. It's a great honour. We cherish them. But it's heartbreaking," Trump said. "Now we've won. It's time to come back." Mark Dubowitz, the chief executive officer of the Foundation for Defense of Democracies who has closely advised the Trump administration on Iran policy, said that "pulling US troops out of Syria would be a gift to Putin and to the mullahs in Tehran. And it would be a disastrous gift for the region." The US military is working to carry out Trump's order quickly, according to one official with knowledge of the plan.

But it wasn't clear what the President's decision would mean for vulnerable Kurdish allies. Turkey – a NATO ally – views the Kurdish fighters as terrorists, and President Recep Tayyip Erdogan has vowed to crush them. Trump's order was met with silence in Ankara, where the foreign ministry and Erdogan's office refrained from making any immediate public comments on the news. Turkish officials expressed caution as the details of the US plan remained unclear. Islamic State, pictured in the group's defacto capital of Raqqa in 2014, have been all but defeated. Credit:AP In a White House statement after Trump's tweet, spokeswoman Sarah Huckabee Sanders said America has "started returning United States troops home as we transition to the next phase of this campaign," although she didn't comment on the pace of that withdrawal. "The United States and our allies stand ready to re-engage at all levels to defend American interests whenever necessary," she added.

Loading Taking time As recently as Tuesday, administration officials disputed the idea that Islamic State is defeated and suggested US involvement would continue. "If we've learnt one thing over the years, enduring defeat of a group like this means you can't just defeat their physical space and then leave," Brett McGurk, the administration's special envoy to the global coalition to defeat ISIS, said on December 11. "You have to make sure the internal security forces are in place to ensure that those gains, security gains, are enduring. So that will take some time."

But Trump has long pressed the military to withdraw from Syria, saying in April that he would make a decision "very quickly." "I want to get out, I want to bring the troops back home, I want to start rebuilding our nation," Trump said at a news conference at the time. He added that "our primary mission" of fighting Islamic State is "almost completed." Even after Trump's announcement, Pentagon spokeswoman Dana White said "the campaign against ISIS is not over." But she offered little insight on the withdrawal, saying in a statement that largely repeated White House talking points that "for force protection and operational security reasons we will not provide further details". Contrasting with the president's declaration of victory, it was less than two weeks ago that Mattis said "there's more work to be done" in Syria. Referring to veteran Islamic State fighters still holding out in the Syrian conflict, Mattis said, "That hardened core means tough fighting there plus the potential for it to try to become more influential worldwide. Influential meaning inspiring attacks by surrogates, by those who've pledged allegiance to them."

Israel's concern Behind the scenes, Israel has supported a continuing US presence, arguing that it helps counter pro-Iranian forces such as Hezbollah. Publicly, Prime Minister Benjamin Netanyahu was supportive, saying on Wednesday that he was informed of the decision by Trump on Monday. "The American administration told me that it is the President's intention to withdraw their forces from Syria," Netanyahu said in a statement. "They made it clear that they have other ways of expressing their influence in the area. In any case we will take care to maintain the security of Israel and to defend ourselves in this area." Andrew Tabler, a Syria expert at the Washington Institute for Near East Policy, said the US plan appears to have resulted at least in part from recent talks between Trump and Erdogan.