The US-led coalition against Islamic State has begun the process of withdrawing from Syria, a spokesman says, indicating the start of a US pull-out that has been clouded by mixed messages from Washington.
US President Donald Trump's announcement last month that he had decided to withdraw 2000 US troops stunned allies that have joined Washington in the battle against Islamic State in Syria.
Senior US officials were shocked too, among them Defence Secretary Jim Mattis, who quit in protest.
The coalition "has begun the process of our deliberate withdrawal from Syria. Out of concern for operational security, we will not discuss specific timelines, locations or troop movements," Colonel Sean Ryan said on Friday.
Russia, which has deployed forces into Syria in support of the Damascus government, said it had the impression that the United States wanted to stay despite the announced withdrawal of US troops, RIA news agency reported.
The US decision has injected new uncertainties into the eight-year long Syrian war including how a resulting security vacuum will be filled across a swathe of northern and eastern Syria where the US forces are stationed.
On the one hand, Turkey aims to pursue a campaign against Kurdish forces that have allied with the United States, and on the other the Russia and Iran-backed Syrian government sees the chance to recover a huge chunk of territory.
US National Security Adviser John Bolton suggested on Tuesday that protecting Washington's Kurdish allies would be a pre-condition of the US withdrawal. That drew a rebuke from Turkish President Tayyip Erdogan who called his comments "a serious mistake".
US Secretary of State Mike Pompeo, who has been touring the Middle East this week to reassure allies of Washington's commitment to regional security, said on Thursday the withdrawal would not be scuppered despite the Turkish threats.
The Kurdish groups that control the north have turned to Moscow and Damascus in the hope of striking a political deal that will stave off Turkey and shield their autonomy in the north.
Maria Zakharova, a Russian Foreign Ministry spokeswoman, said it was important for Syrian Kurds and the Syrian government to start talking to each other in light of the US withdrawal plans.
She also said the territory previously controlled by the United States should be transferred to the Syrian government.
Turkey views the US-backed YPG Syrian Kurdish militia as an extension of the Kurdistan Workers' Party (PKK), which has waged a 34-year insurgency in Turkey for Kurdish political and cultural rights, mostly in southeastern areas near Syria.
A Kurdish politician told Reuters last week the Kurds had presented Moscow with a road-map for a deal with Damascus. Syria's deputy foreign minister said on Wednesday he was optimistic about renewed dialogue with the Kurds.