President Donald Trump’s Dec. 19 tweet announcing an immediate and unconditional withdrawal from Syria has rendered the United States a lame duck in the war-torn country. Although Trump and his aides clarified later the withdrawal would not happen “that quickly,” the fact remains that American troops will be leaving Syria in a foreseeable future, raising the question of who will fill the vacuum after US forces depart from Manbij and the area east to the Euphrates River, where they are currently deployed.

First, of course, one needs to be mindful that a real vacuum could emerge if beyond withdrawing its troops, Washington retracts its military commitments to its ally in the region, the Syrian Democratic Forces (SDF). What is referred to as “east of the Euphrates” is a vast area where the United States has imposed deterrence through air power and 2,000 special forces troops. The essence of this deterrence, however, is not in the number of troops but the commitment of the United States as a superpower.

Should American deterrence end, the SDF — whose backbone is made of the Kurdish People’s Protection Units (YPG) — will obviously lack deterrence on its own against the forces in line to fill the vacuum. The first such force that comes to mind is naturally Russia and then, to some extent, the Iranian-sponsored Syrian regime, for “east of the Euphrates” is Syrian territory after all and the regime has clearly prevailed in the eight-year war thanks to its allies.

That Turkey is also tossing its hat in the ring became evident in a Jan. 7 opinion piece in the New York Times signed by President Recep Tayyip Erdogan and headlined “Erdogan: Trump is right on Syria. Turkey can get the job done.”