There is more confusion over the future of the US military presence in Syria after officials said they had begun to withdraw — but only equipment, and not yet any troops.
Colonel Sean Ryan, a spokesman for the US-led coalition in the country, said it "has begun the process of our deliberate withdrawal from Syria."
He added: "Out of concern for operational security, we will not discuss specific timelines, locations or troop movements."
But it has emerged the number of troops might actually increase slightly in Syria to help protect the final process of pulling out, the New York Times reported.
Allies were stunned and Donald Trump's defence secretary resigned after the pullout was announced last month.
Russia said it was beginning to suspect the US did not actually want to leave.
"At the moment we have an impression that they are leaving and looking for a reason to stay — as it was said in one of the popular movies," said Maria Zakharova, the Russian Foreign Ministry's spokeswoman.
"For this reason we have said repeatedly that we would like to have an insight into the (U.S) strategy."
The Russia and Iran-backed Syrian government sees the withdrawal as an opportunity to recover a large chunk of territory it lost with the outbreak of the country's civil war.
Meanwhile Turkey is deploying its own troops to the Syrian border, sparking fears of a clash with the local Kurdish YPG militia, a US ally that the Turkish government considers a terrorist organisation.
Residents near Iraqi border crossings that are typically used by US forces going in and out of Syria said they had seen no obvious or large-scale movement of American ground forces on Friday.
Secretary of State Mike Pompeo has been touring the Middle East this week in an effort to reassure American partners that his country remains committed to regional security.