Japanese F-15 fighter jets on Thursday conducted an air exercise with U.S. B1-B bombers and F-35 stealth fighters in skies south of the Korean peninsula, two days after North Korea launched a ballistic missile over northern Japan.

The exercise around Japan's southern island of Kyushu involved two U.S. Air Force B-1B Lancer bombers flying from Andersen Air Force Base on the U.S. Pacific island territory of Guam and four F-35B stealth jets from the Iwakuni U.S. Marine Corp Air Station in Japan.

They were joined by two Japanese F-15 jet fighters, Japan’s Air Self Defence Force (ASDF) said in a news release.

The U.S. aircraft went on to conduct drills with South Korean military jets, the Japanese air force said.

North Korea this week fired a new strategic ballistic missile called the Hwasong-12 over northern Japan that reached an altitude of 550km (341.75 miles) before splashing down in the Pacific Ocean.