An American military official says the U.S.-led military coalition has begun the process of withdrawing troops from Syria.

Col. Sean Ryan, spokesman for the U.S.-coalition fighting the Islamic State group, says the U.S. started "the process of our deliberate withdrawal from Syria."

In a statement emailed to The Associated Press on Friday, he declined to discuss specific timelines or locations or troops movements out of concern for operational security.

>> Read more: U.S. will work to expel 'every last Iranian boot' from Syria, Pompeo says in Cairo ■ Erdogan rejoiced at Trump's Syria pullout. Then he realized it was Trump

The Britain-based Syrian Observatory for Human Rights, which monitors the conflict in Syria through a network of activists on the ground, said the withdrawal began Thursday night.

It said a convoy of about 10 armored vehicles, in addition to some trucks, pulled out from Syria's northeastern town of Rmeilan into Iraq.

Russia's foreign ministry said on Friday it had the impression that the U.S. wanted to stay in Syria despite the announced withdrawal, RIA news agency reported.

The U.S. announcement comes a day after Turkish Foreign Minister Mevlut Cavusoglu said a military operation in northern Syria against the Kurdish YPG militia, which is allied with the U.S., is not dependent on the withdrawal of American forces.

“If the [pullout] is put off with ridiculous excuses like Turks are massacring Kurds, which do not reflect the reality, we will implement this decision,” Çavuşoğlu said, referring to Turkey's threat to launch an incursion into Kurdish controlled Syria.

In an interview with broadcaster NTV, Cavusoglu said it was not realistic to expect the United States to fully collect weapons it gave to its YPG ally, which Ankara views as a terrorist group.

U.S. Secretary of State Mike Pompeo also addressed the issue in a speech in Cairo on Thursday. Regarding Syria, Pompeo said, "the United States will use diplomacy and work with our partners to expel every last Iranian boot, and work through the UN-led process to bring peace and stability to the long-suffering Syrian people."

This follows U.S. President Donald Trump's recent remark last week that Iran "can do what they want" in Syria.

Trump made the comment during a conversation with reporters at the end of a cabinet meeting in the White House. “Iran is pulling people out of Syria, but they can frankly do whatever they want there,” the U.S. president said.

Trump also refused to directly answer a question about the timeline of the U.S. withdrawal from Syria, saying only that it will happen “over a period of time."