TOKYO — Japanese and US forces conducted a joint exercise with six fighters over the Sea of Japan on Tuesday, Tokyo’s Defense Ministry said, following North Korea’s missile launches two days ago.

Four F-15 fighter jets from the Japan Air Self-Defense Force Chitose Air Base and two F-16s from US Misawa Air Base, both in northern Japan, participated in the bilateral exercise, the ministry said in a press release.

“This bilateral exercise reaffirms the coordination of the Japan Air Self-Defense Force and the US Armed Forces, demonstrating the close cooperation between Japan and the US in responding to any situation, and further strengthens the ironclad Japan-US alliance,” the ministry said.

The ministry underlined an increasingly severe security environment, including North Korea’s repeated ballistic missile launches.

The two forces routinely work together and maintain high levels of operational readiness to respond to any situation to defend our nations, contributing to regional peace and stability, it added.

The joint flight came as North Korea fired eight short-range ballistic missiles into the sea Sunday. Japanese and US fighter jets also conducted a similar joint flight after North Korea launched three ballistic missiles, including an apparent intercontinental ballistic missile, on May 25.

Japan and the United States conducted a joint fighter jet drill over the Sea of Japan on Tuesday for the second time in two weeks, days after North Korea’s latest missile launches amid growing fears of a possible nuclear test.

The exercise, following Pyongyang’s test-firing of eight short-range ballistic missiles toward the sea on Sunday, was intended to showcase “strong will of Japan and the United States to respond to every situation” and the two countries’ “close collaboration,” and to further strengthen their alliance, Japan’s Defense Ministry said.

If Pyongyang conducts its seventh nuclear test, it would be its first since 2017. The reclusive nation has carried out 17 missile tests since the beginning of this year, including firing of cruise missiles.

Washington is concerned that Pyongyang could carry out a nuclear test “in the coming days,” State Department spokesman Ned Price said Monday. — Agencies