The U.S. and Japanese air forces conducted a joint exercise over the Sea of Japan (East Sea) on Thursday to strengthen deterrence against North Korean missile threats, according to Tokyo, after the latest DPRK missile test triggered evacuation orders in Japan.

Four U.S. F-16 and four Japanese F-2 fighter jets took part in the drills aimed at improving the allies’ response “amid an increasingly severe security environment surrounding Japan,” Japan’s Joint Staff said in a press release Thursday.