The U.S. military on Thursday shot down a Turkish drone that had come in too close to U.S. troops on the ground in Hasakah, Syria, two U.S. officials told The Associated Press. One official said the drone was armed.

The official also said the shootdown was ordered after more than a dozen calls to Turkish military officials stating U.S. forces were on the ground in the area and the U.S. military would engage in self-defense if the drone didn’t leave the area.

The other official said the drone had been flying in an “unsafe” and “unsychronized” manner. Typically, the U.S. and Turkish militaries, which are NATO allies, work in close coordination in conducting air maneuvers. The officials spoke on condition of anonymity to discuss the incident before an announcement.

The U.S. has about 900 troops in Syria conducting missions to counter Islamic State group militants.