President Donald Trump has made a surprise Christmas visit to US troops in Iraq.

Making his first trip to a conflict zone in almost two years as president, Mr Trump touched down at the Al Asad Air Base west of Baghdad after an overnight flight from Washington, along with first lady Melania Trump, a small group of aides, Secret Service agents, and a pool of reporters.

“President Trump and the first lady travelled to Iraq late on Christmas night to visit with our troops and senior military leadership to thank them for their service, their success, and their sacrifice and to wish them a Merry Christmas,” White House press secretary Sarah Huckabee Sanders said in a statement.

Mr Trump’s surprise visit comes days after he announced his decision to withdraw American troops from Syria and to significantly reduce the US military presence in Afghanistan – a move that that prompted defence secretary James Mattis to resign.

On his stop in Iraq, Mr Trump defended his decision to pull out the 2,000 troops from Syria, which he has said was made possible by the defeat of Isis.

“We want peace and the best way to have peace is through strength,” he told troops wearing camouflage fatigues in a hangar as he concluded his visit. He said some troops “can now return home to their families”.

“Our presence in Syria was not open-ended and it was never intended to be permanent,” he added.

"We're no longer the suckers, folks," Trump told the troops at the base. "We're respected again as a nation."

Mr Trump said: “A lot of people are going to come around to my way of thinking.” Last week, the president claimed in a tweet that Isis has been “defeated” in Syria.

But when it comes to Iraq, however, Mr Trump said he has “no plans at all” to remove more than 5,000 US troops stationed there.

Mr Trump's visit angered Iraqi officials and two major political parties in the country condemned his visit.

The president will also visit US troops at Ramstein Air Base in Germany before he heads back to Washington.