Abandoned by the US, there are unpalatable choices in every direction for the Syrian Kurds

What political aspirations of autonomy they can extract will depend in significant part on what Ankara will allow – a dire turnaround for the Kurds, who pinned hopes on autonomy

Syrian Kurds marching in Afrin, northern Syria, march in support of jailed PKK leader Abdullah Ocalan. AFP

It apparently took a mere phone call for Turkish President Recep Tayyip Erdogan to persuade his US counterpart to withdraw troops from Syria. Sudden changes in policy can be politically expedient when they unexpectedly wrong-foot an opponent. Yet by suddenly declaring US troops would be leaving, Donald Trump has managed to wrong-foot his own allies and administration instead.

At a stroke, the US president has changed the political landscape of Syria, handing immense leverage to his rivals and adversaries.

Turkey now has great power to influence how the Syrian war ends – and what happens to the political aspirations of Kurds in that region, a group which, until just days ago, had relied on the US to be a stable ally. There is now almost nothing and no one in its way to fulfil its border strategy in Syria.

Of all the western allies engaged in Syria – Nato countries, Arab and Kurdish allies – none will benefit from this sudden withdrawal. It is dubious whether it will benefit the fight against ISIS, as Mr Erdogan has promised. Indeed, it is doubtful it will benefit anyone other than Mr Erdogan himself, as well as every adversary to the US inside Syria – the regime, Russia and Iran. All will be adjusting their plans in reaction to the news.

In one aspect, though, nothing will change. Turkey will plough on with its mission in northern Syria to curb the ambitions of Syrian Kurdish groups for greater autonomy.

Ankara has always chafed at Syrian Kurdish groups controlling areas west of the Euphrates, arguing that they are allied with the militant PKK-led Kurdish insurgency inside Turkey. More than once, Turkey has threatened to remove Kurdish groups from the city of Manbij in northern Syria by force. It was the latest threat to do so that sparked the current crisis and apparently led to Mr Trump pulling troops out.

That specific operation may or may not go ahead – Turkish troops and Ankara-backed Syrian rebel fighters are reportedly massing on the outskirts of Manbij at the moment, while a delegation of Syrian Kurds is in Moscow in a bid to halt a possible offensive – but it matters little. With the US leaving, the Syrian Kurds are largely at the mercy of the Turks, unless Russia or the Syrian regime decide to intervene.

Because if the departure of US troops has left the Syrian Kurds militarily exposed to Turkish aggression, it has also left them politically at the whims of the Assad regime.

The Syrian Kurdish bloc was the only political entity within Syria over which the US had influence. That meant that in peace negotiations and in discussions over the future of the country, there was still a way for the US to maintain some control. Yet after one phone call, Mr Trump has given that up.

Now into that power vacuum in north-eastern Syria will step the regime. Already there have been rumours that the Kurds will ask the regime to return to the Kurdish areas to defend them against the Turks. Caught between the regime in Damascus and the government in Ankara, it seems likely that the Kurds will return to the regime fold – but, crucially, on vastly compromised terms.

With the Assad regime weak and Russia so far indifferent to what happens on the border, as long as it doesn't affect its core interests, Turkey is now the main power-broker in that region. Its border policy, which is to stop the political unity of the Kurdish groups, will be hard to resist. What the Syrian Kurds can salvage from this betrayal by the US will depend in significant part on what Ankara will allow – a dire turnaround for the Kurds, who have pinned so many hopes on aspirations of autonomy or separatism and will find this especially difficult to swallow.

It is entirely possible, perhaps even likely now, that the Syrian Kurds will end the war on a much weaker footing than when they first entered the fold. They will be more beholden to the Assad regime as a protector against Turkey but will be viewed with immense suspicion in Damascus because of their push for autonomy. At the same time, Turkey will seek an expanded role in the entire border region, in significant part to make sure the Kurds cannot regroup.

At one time, it looked as if the Kurds could form an alliance with the regime against Turkey. Now, given their political weakness, Damascus might find it more politically expedient to let Turkey grind down Kurdish armed fighters, before cutting a deal to defend what remains under the guise of “territorial sovereignty”. In every direction, there are unpalatable choices for America's former allies.

If it seems as if one phone call has essentially vindicated Mr Erdogan's border strategy, there is one additional element that might complicate his celebrations – because tucked into the implications of US withdrawal is a potentially poisoned chalice.

In the days after Mr Trump's announcement, Mr Erdogan again pledged to destroy “PKK elements” in northern Syria but this time it was with the introduction of a new phrase and target – “ISIS remnants”.

With the US gone, Turkey is the only Nato member with a major military presence on the ground in Syria, allowing Mr Erdogan to claim that he has now taken on the mantle of ridding the country of ISIS. Expect him to enthusiastically adopt that line and claim to be defending Europe and the Arab world from its scourge.

And therein lies the danger. Because ISIS turned out to be a vastly more dangerous threat than anyone first imagined, certainly more dangerous than Barack Obama's dismissive analogy six years ago of the group being a minor sports team compared to Al Qaeda. If Mr Erdogan remains in control of the region and ISIS re-emerge, Turkey will be the first target in its crosshairs.

Mr Erdogan might have been handed victory in his race to secure the border. But if he thinks he has been handed the ISIS baton minutes from the finish line, he ought to consider how much further the race against ISIS still has to run.