Turkey said it will send home Russian missile experts overseeing the S-400 air defense technology that has strained ties with the United States.

The remarks, which come ahead of a planned meeting between Turkish President Recep Tayyip Erdogan and President Joe Biden on the sidelines of a NATO summit in Brussels mid-June, signal Ankara’s readiness to compromise on one element of U.S. concerns. Washington has said Turkey should end the presence of Russian personnel in the country to help with training and assembly of the missiles.

However Turkish Foreign Minister Mevlut Cavusoglu, who said the system would be under Turkish control when the experts left, reiterated Ankara would not budge on Washington’s broader demand to get rid of the missiles in order for related U.S. sanctions to be lifted. He rejected U.S. calls on Turkey not to activate the missiles. “It is not possible to accept calls from another country to “not use” them,” he said.