The US is apparently slowing its planned troop withdrawal from Syria, despite the president announcing an abrupt end to American presence in the country just weeks ago.

Donald Trump, in a defiant tweet on Monday, wrote: “Isis is mostly gone, we’re slowly sending our troops back home to be with their families, while at the same time fighting Isis remnants.”

The twist was the latest in a series of White House foreign policy gyrations that have contradicted Mr Trump’s senior aides and stunned his allies.

US troops launch mortar against ISIS positions in Syria (AP)

It remains unclear if the White House has modified plans for the withdrawal, which by some accounts has already begun.

Hundreds of UK and French military personnel, including Special Forces commandos, are based alongside US troops in northern Syria as part of four-year international effort to defeat Isis.

A top US senator briefed by Mr Trump on Sunday added to the confusion. Senator Lindsey Graham, an influential and outspoken South Carolina Republican, said the US would not allow for a chaotic withdrawal of American military personnel from northern Syria and would prevent Iran from filling any vacuum.

He tweeted: “The President will make sure any withdrawal from Syria will be done in a fashion to ensure Isis is permanently destroyed; Iran doesn’t fill in the back end; and our Kurdish allies are protected.” He added Mr Trump was “talking with our commanders and working with our allies to make sure these three objectives are met as we implement the withdrawal”.

Mr Graham told reporters after the meeting that Mr Trump “made me feel a lot better about where we’re headed in Syria”.

But many questions about US policy in Syria remain. Of Mr Graham’s three aims, Mr Trump only mentioned wiping out Isis. Iran is a key ally of the Syrian regime, and keeping it and its many proxies out of northeast Syria would be challenging if Damascus forces take over.

'They're all coming back and they're coming back now' Trump declares victory over Isis in Syria

Protecting US allies would further anger Turkey, which opposes the Kurdish-led force. The northern Syria region, now called Rojava, is controlled by a leftist Kurdish organisation that is allied with the Kurdistan Workers’ Party (PKK), an outlawed group listed as a terrorist organisation by the US, EU, and Turkey.

Turkish President Recep Tayyip Erdogan’s top adviser Ibrahim Kalin chided Mr Graham on Monday. “You know and have stated publicly more than anyone else the direct link between the terrorist PKK and its Syria branches,” he wrote. “Terrorists cannot be your allies. Just as Isis doesn’t represent Muslims, PKK doesn’t represent Kurds in Syria or elsewhere.”

Mr Graham, a sometimes critic of Mr Trump whose support is vital for some of the president’s domestic policies, is a foreign policy hawk who frequently advocates US military intervention abroad. Mr Trump seems to have a knack for telling key Republican Party officials what they want to hear, with his foreign policy calculations based on US domestic politics rather than global affairs.

The president tweeted on Monday: “I campaigned on getting out of Syria and other places. Now, when I start getting out, the Fake News Media, or some failed generals who were unable to do the job before I arrived, like to complain about me and my tactics, which are working.”

A Turkish tank is transported near the the border with Syria this month (AP)

Many Middle East watchers have questioned the presence of the 2,000 troops in Syria. But they have criticised Trump’s approach to pulling out despite the objections of his own key deputies, without consulting local partners in Syria or allied UK and French military personnel.

The announcement spurred the resignations of defence secretary James Mattis and Isis policy envoy Brett McGurk, as well as a scramble for turf by regional state and non-state powers.

Turkey has vowed to wipe out the proto-state Rojava, which Kurds have established along its border. The Syrian regime, too, backed by Russia and Iran, seeks to regain control over the area, which includes oil wells and some prime agricultural land and trade routes.

Already Turkish forces have arrayed along the Kurdish enclave, Israel has launched fresh airstrikes, and Kurds have invited Syrian ground forces as protection.