US President Donald Trump has said he will lift sanctions on Turkey after the Nato ally agreed to permanently stop fighting Kurdish forces in Syria.

Mr Trump made the announcement as he defended his decision to withdraw American troops, saying the US should not be the world’s policeman.

“We’re getting out,” Mr Trump said at the White House, asserting that tens of thousands of Kurdish lives were saved as the result of his actions.

“Let someone else fight over this long, blood-stained sand,” he added.

Mr Trump warned that if Turkey does not honour its pledge for a permanent ceasefire, he will not hesitate to reimpose sanctions.

Earlier this month, Mr Trump halted negotiations on trade deal with Turkey, raised steel tariffs back up to 50% and imposed sanctions on three senior Turkish officials and Turkey’s defence and energy ministries.

“The job of our military is not to police the world,” Mr Trump said. “Other nations must step up and do their fair share. Today’s breakthrough is a critical step in that direction.”

Mr Trump earlier in October ordered the bulk of the approximately 1,000 US troops in Syria to withdraw after Turkey’s president, Recep Tayyip Erdogan, told Mr Trump in a phone call that Turkish forces were set to invade north-eastern Syria.

Turkey’s goal was to push back the US-allied Kurdish fighters. Turkey views the Kurds as terrorists and an ever-present threat along its southern border with Syria.

The US pullout was seen as an abandonment of Kurdish fighters, who have incurred thousands of casualties as they fought with US forces against so-called Islamic State militants.

The US troops left, but the conflict was not without repercussions.

Turkish soldiers in Syria
Turkish soldiers with Turkey-backed opposition fighters on a building next to their flags in a town in north-eastern Syria (Ugur Can/DHA via AP)

Mr Trump’s critics say he gave up American influence in the region and signalled to future allies that the United States is no longer a reliable partner.

More than 176,000 people have been displaced by the Turkish offensive and about 500 IS fighters gained freedom during the conflict.

“There were a few that got out, a small number relatively speaking,” Mr Trump said. “They’ve been largely recaptured.”

Turkey is taking control of areas of Syria that it captured in its invasion. Russian and Syrian forces are now overseeing the rest of the border region, leaving the United States with little influence in the region.

Mr Trump said he would “bring our soldiers home” from Syria, but then recalibrated and his administration plans to shift more than 700 to western Iraq.

Those troops, however, do not have permission to stay in Iraq permanently. Iraq’s defence minister, Najah al-Shammari, said the US troops will leave the country within four weeks.

Defence secretary Mark Esper visited the Iraqi capital on Wednesday, a day after Russia and Turkey reached an agreement that would send their forces along nearly the entire north-eastern border to fill the void left when US forces left. Between 200 and 300 US troops will remain at a southern Syrian outpost.