Ankara - President Donald Trump’s decision to pull US troops out of Syria has triggered a scramble among international powers and local forces to figure out how to fill the potentially destabilising vacuum the Americans will leave behind.

But as the diplomacy drags on, it is becoming clear there is no readily apparent arrangement that will satisfy the competing concerns and agendas of all the parties involved - and that none seems likely to emerge soon.

Turkey, Russia, America’s Syrian Kurdish allies and the Syrian regime all have a strategic interest in any arrangement for the future of northern Syria, yet most of their demands are diametrically opposed. That they are not all talking to one another only compounds the difficulty of reaching a solution.

Turkey considers the Kurdish forces to be terrorists and wants to create a Turkish-controlled buffer zone to keep them away from its border. The United States’ Kurdish allies, who fear persecution at Turkish hands, want the Turks kept out.

The Trump administration wants to satisfy both sides, making good on its contradictory promises to protect its Kurdish allies and to give Turkey a stake in the area.

The Kurds would prefer a return of Syrian regime authority in the area they control. But one of Syrian President Bashar Al Assad’s closest allies is Iran, and the Trump administration object to any plan that allows the Iranians to maintain - much less extend - their influence in Syria.

The various positions are “irreconcilable,” said Aaron Stein, director of the Middle East programme at the Philadelphia-based Foreign Policy Research Institute. “They are massive issues. The US is throwing a lot at this, but they are just irreconcilable.”

The Pentagon still has not announced a date for the withdrawal, but the questions of how and when it will happen is gaining urgency as Daesh’s once vast “caliphate” dwindles. The Kurdish led-Syrian Democratic Forces (SDF), backed by US air strikes, have the Daesh holdouts pinned down in one last village in the southeastern Syrian desert.

After initially announcing in December the troops would be pulled out right away, Trump subsequently said they would remain until the last pocket of Daesh territory had been vanquished - and that could come as early as next week, he said on Wednesday. The Wall Street Journal reported on Friday that the US military is eyeing an April deadline for the troops to leave.

US officials say they are committed to negotiating a handover agreement, but they also stress the troops will pull out regardless.

“We are withdrawing. There should be no doubt to that,” said a senior US official.

That raises the prospect of a no-deal withdrawal that could plunge the region into chaos and, potentially, conflict as the competing powers pile in to stake their claims. Turkey is threatening to invade the area if its demands are not met. The Syrian government has deployed troops to the south of the region, and Daesh is already trying to regroup in areas from which it has been pushed out. A power vacuum or new conflict could help Daesh make a comeback, military officials say.

To avert such an outcome, intensive diplomacy is underway between the United States and Turkey, aimed primarily at fulfilling Trump’s promise to Turkish President Recep Tayyip Erdogan in their December telephone conversation that the area of northeastern Syria where US troops are currently located is “yours.” James Jeffrey, the US envoy to the anti-Daesh coalition, has been travelling to Turkey, and Turkish officials have visited Washington for talks there.

The focus of these discussion is on meeting Turkish demands for what both sides are terming a “safe” zone in Syria along the Turkish border. But the talks have revealed only that the United States and Turkey have vastly differing interpretations of what counts as “safe.”

“The United States wants a safe zone to protect Kurds from the Turkish army and for Turkey it is the exact opposite,” said Nihat Ali Ozcan, a military analyst with the Tepev think tank in Ankara. “How can two countries cooperate when their goals are that much opposed.”

Washington is meanwhile also exploring the possibility of maintaining overall American control without US troops on the ground, US officials say. Under that scenario, small contingents of British and French troops, who are already operating alongside Americans, would remain in the area together with the Syrian Democratic Forces and perhaps also with private US military contractors and United Nations observers, while the United States provides air cover.

That is the outcome the Kurds say they would like most. But otherwise, they have stated a clear preference for a return of Syrian regime authority over any arrangement that gives Turkey a role.

It is not clear however whether Damascus is prepared to make the kind of concessions the Kurds are seeking to guarantee the autonomy they have secured recently with the support of US troops.