US forces in northern Syria have been ordered to leave the country, days after the start of the Turkish military operation, while France is considering the same option after the US decision, media sources said.

A US official told AFP on Monday that all 1,000 US troops in northern Syria had been ordered to leave the country in light of the Turkish offensive against Kurdish forces in the region.

"We are implementing this," the official, who declined to be identified, said. He pointed out that it includes "all" military personnel deployed in Syria, "except those in the military base of al-Tanf in the south of the country, which includes about 150 US military."

US Defense Secretary Mark Esper announced on Sunday that President Donald Trump had ordered the withdrawal of about 1,000 troops from northern Syria, without specifying whether they would leave the country or would only be driven out of areas where fighting between Turkish troops and Kurdish units designated as terrorist by Turkey.

"It was a very smart decision not to engage in heavy fighting along the Turkish border, contrary to what usually happens," Trump said Monday.

"The Kurds and Turkey have been fighting for several years," he said. "Others may want to fight with one side. Let them do it! We are watching the situation very closely."

The president hinted that the Kurds are deliberately releasing "some" prisoners from ISIS operatives, to push the United States to continue its intervention in northeastern Syria.

Limited French options
In the same context, sources told Agence France-Presse that France may have no choice but to withdraw its troops from the coalition against the Islamic State in northern Syria after the US President's decision to withdraw his troops from that region.

Paris is contributing about 1,000 troops to the coalition in Syria and Iraq, and military sources say they include about 200 special forces in northern Syria.

Although the French government has not officially confirmed the presence of special forces in Syria, President Emmanuel Macron implicitly admitted their presence there after a meeting with French defense officials on Sunday.

A statement by the French presidency following a meeting of the Defense and National Security Council in Paris chaired by Macron said measures would be taken "to ensure the safety of French military and civilian personnel in the region."

France has also announced that it will take steps to enhance national security.

A spokesman for the French armed forces declined to give further details of the announcement for security reasons.

"We have never hidden the fact that countries with small military units will not be able to survive if the United States withdraws," a French diplomatic source told AFP.

The Times reported last week that Britain was also ready to withdraw its special forces operating in northern Syria should US troops withdraw.