An aide to Turkish president Recep Erdogan told a radio show that the U.S. soldiers in northern Syria are not safe from Turkish bombs, saying “we won’t be considering the fact that there are armored American vehicles… all of a sudden, by accident, a few rockets can hit them.”

His comments come as a politically delicate situation has been transpiring in northern Syria with American special operations forces in the middle. Abandoning hope of American-trained militia and rebel groups from offering significant resistance against Assad or the Islamic State in Syria, the U.S. has instead turned to reliable Kurdish fighters to be the boots on the ground.

The problem lies with key NATO ally Turkey, who considers some of the Kurdish units the U.S. is supporting to be terrorist groups. Turkey has launched its own military incursion into northern Syria, titled “Operation Euphrates Shield,” which has more to do with limiting Kurdish territorial gains along the Turkey-Syria border than eliminating the Islamic State and other jihadist groups operating in the security vacuum of Syria.

An American show of force in the area, placing members of the 75th Ranger Regiment and other special operations forces between members of the U.S. backed Syrian Democratic Forces (SDF) and the Turkish military, led to the possibly threatening remarks by the Erdogan aide.