The United States is in active contact with Turkey on the formation of a possible safe zone in northern Syria, a State Department official said Tuesday.

"We are actively engaging with Turkey on this, and that is part of our efforts to ensure a safe withdrawal of United States forces and a stabilized northeast Syria," Deputy Spokesperson Robert Palladino told a press conference.

In December, President Donald Trump made a surprise announcement that the U.S. would be withdrawing all of its troops from Syria and said Daesh had been defeated in the country

Since then, however, no troops have been withdrawn, and the Pentagon confirmed last month that additional troops were being sent to protect American forces and equipment as they prepare to leave.

Turkey has repeatedly raised security concerns after the announced U.S. troop withdrawal, saying the pullout would give room to the PYD/YPG, the Syrian offshoot of the PKK terror organization, to expand their operations.

Palladino said Washington takes Ankara’s "legitimate security concerns seriously".

"We take them into account in our activities and we have ongoing coordination. We’re not going to discuss specifics on these talks, but they continue," he said.

Palladino said the withdrawal of troops is a "tactical change, but not a change in our mission".