In the early hours of Wednesday, Turkey said it had been informed by the U.S. that their withdrawal from the border areas had been "completed".
Turkish President Recep Tayyip Erdoğan announced on Tuesday that Turkey and Russian Federation had reached a "historic" agreement that would remove all Syrian Kurdish fighters from the Syria-Turkey border region.
The statement came the morning after Turkish President Recep Tayyip Erdogan and Russian President Vladimir Putin announced a separate deal for their forces to jointly patrol nearly the entire north-eastern Syrian border after the Kurdish withdrawal.
Both presidents agreed to commit to "the preservation of the political unity and territorial integrity of Syria and the protection of Turkey's national security" in a joint memorandum.
The deal was widely perceived as good news for Ankara and a poor result for Syria's Kurdish forces, building as it does on the US' agreement last week that Turkey has a right to a buffer zone on its border at their expense.
The Trump administration has offered to remove economic sanctions on Ankara if the fighting stops - another of Erdogan's key demands - although a time frame has not been outlined.
The temporary freeze of the situation on the ground in northeast Syria with the establishment of the Turkish safe zone and joint Russian-Turkish patrols might bring new opportunities for the Kremlin.
Erdogan said last week he was not bothered by the Damascus regime's return as what mattered to Ankara was pushing back the Kurdish fighters from the safe zone.
The US agreed to pull its troops out of northern Syria in advance of the Turkish incursion despite having armed YPG/PKK militants in the past in their fight against Daesh.
Turkey's primary objective "was to push the USA out and to break the SDF as the governing entity and as the legitimate political and military actor in the Syrian space".
In a further sign of growing ties between Ankara and Moscow, which have alarmed the U.S. administration, the head of Russia's defense sales agency was quoted by the Interfax news agency on Wednesday as saying Moscow could deliver more S-400 missile defense systems to Turkey.
Turkey's president has threatened to resume an offensive in north-east Syria unless Kurdish fighters withdraw from the border before a ceasefire ends.
The United States, meanwhile, ran into a new hitch in getting its troops out of Syria, with neighboring Iraq's military saying Tuesday that the American forces did not have permission to stay on its territory.
Amid fears the Americans' departure will revive IS, Esper is considering keeping some troops in Syria to protect oil fields held by Kurdish-led fighters, backing away from the full withdrawal first touted by Trump.
"All will have to get out", Erdogan said before the Sochi meeting.
The zone - to which Erdogan wants to relocate some 2 million Syrian refugees residing in Turkey - will extend 20 miles deep into Syria along an east-west stretch of the border.
The Kremlin said it hoped Mr Erdogan would be able to provide Mr Putin with more information about Ankara's plans for north-east Syria, and was also studying what it described as a new idea from Germany for an internationally controlled security zone in northern Syria involving Turkey and Russian Federation.
Mr Erdogan has said he could accept the presence of Syrian troops in those areas, as long as the YPG are pushed out.
The Putin-Erdogan deal creates a new reality on the ground where Russian Federation, in effect, becomes a security provider for both the Turks and the Kurds.
Russian Federation and Iran have provided crucial support for Assad in the country's more than eight-year civil war, while Turkey and the United States have backed differing rebel groups.