The Syrian army said a U.S. missile attack on one of its air bases had killed six people and caused extensive damage, adding that it would respond by continuing its campaign to "crush terrorism" and restore peace and security to all of Syria.

A statement from the army command described the attack on Friday as an act of "blatant aggression", saying it had made the United States "a partner" of Islamic State, the Nusra Front and other "terrorist organisations".