The US and its allies in the Syrian conflict have created a tangle of relationships so complex and contradictory that it is nearly impossible for even senior members of the Obama administration to separate them.
During his visit to Ankara on Wednesday, US vice-president Joe Biden said that US-backed Kurdish fighters must return to the east bank of the Euphrates river or risk losing Washington's support.
Turkey has warned that the Kurds' presence in the west is a red line issue which cannot be breached without encountering Turkish resistance. Turkey is determined to prevent the Kurds from establishing a statelet stretching along the Syrian side of the border with Turkey.
Biden’s words were meant to reassure Turkey as its tanks and elite units, along with 1,500 allied Syrian militia, operating with US air cover, drove Islamic State from the border town of Jarablus. Jihadis, arms and ammunition flowed through Jarablus from Turkey to Islamic State’s de facto capital in Raqqa.
Cross-border support
This operation was completed within a day, although Islamic State, also known as Isis, had occupied the town since 2013. It shows that Turkey could have put an end to cross-border support for Isis at any time. This feat also exposes Turkey’s preference for this group over Syrian Kurds who are an offshoot of Turkish Kurds battling Ankara for self-determination.
Less than two weeks ago the US and Syrian Kurds celebrated the rout of Islamic State from Manbij, another strategic town 38km south of Jarablus. US special forces and air cover bolstered the mainly Kurdish fighters, seen by Washington as the most effective weapon against Isis, in the protracted battle for Manbij.
In response to Biden’s remarks, the Kurds have redeployed some units to the west bank of the river, but are unlikely to surrender Manbij, a key asset in the coming battle for Raqqa.
Peace talks
Ahead of the Jarablus operation, the US and Turkey vowed to seal the Turkish-Syrian border. If this is done, the frontier in the west would also have to be closed to the transit of men, weapons and funds to Jaish al-Fatah (Army of Conquest), dominated by Jabhat Fatah al-Sham (the rebranded al-Qaeda affiliate) and Ahrar al-Sham, its radical fundamentalist partner.
Although the US regards al-Qaeda-connected groups to be "terrorist", Washington has not renounced or punished US-"vetted" factions co-operating with al-Qaeda by cutting off arms supplies or aid. Consequently, Syria's northwest border with Turkey is likely to remain open for supplies and men destined for Jaish al-Islam-occupied Idlib province, even though al-Qaeda continues to wield influence there.
US ties to Turkey have bedevilled efforts to reach accommodations with Russia. Moscow was told by Washington it would cut ties to al-Qaeda-supported groups early in 2016 but this has not happened.
Turkey has also blackballed the participation of the US-supported Syrian Kurds in two rounds of peace talks held this year in Geneva.
Russian's foreign minister Sergey Lavrov has also reminded Washington of its promise to distinguish between al-Qaeda-fostered groups and others as Moscow agreed to the UN's 48-hour truce in Aleppo to provide for the delivery of aid.
UN envoy Staffan de Mistura said other sides had still to accept. “We are ready, trucks are ready and they can leave any time we get that message.”