US Secretary of Defense Mark Esper called on Turkey to halt the invasion of northeast Syria, warning that this could have serious consequences for Ankara.

In phone talks with Turkish Minister of Defense Hulusi Akar, Esper confirmed that the US is opposed to Turkey’s attack on the predominantly Kurdish region, since they risk nullifying the successes of the coalition fighting to eliminate the Islamic State, the Pentagon said in a statement. 

Esper also urged Turkey to cease operations in northeastern Syria.

Although the head of the Pentagon confirmed that we value our strategic bilateral relations, this invasion could have serious consequences for Turkey, the statement said.

Esper told Akar that ending the Turkish invasion would open the door for negotiations to find a common way to discount the situation before it becomes irreparable.