North Korea fired what appeared to be multiple short-range ballistic missiles off its east coast, South Korea’s military said on Thursday, in what may be a performance test of various projectiles for export.

The missiles were launched from Wonsan, North Korea’s eastern coastal city, around 8:10 a.m. (2310 GMT Wednesday) and flew up to 800 km (497 miles) before splashing down in the sea, the military said in a statement.

South Korea is closely communicating with the US and Japan to share information about the launch, it added.

South Korea’s Joint chiefs of Staff spokesperson Lee Sung-jun declined to comment on the exact number of missiles detected or their characteristics but said at a news briefing the launch may have been to test the performance and flight stability of missiles intended for export.

The Japanese government also said it detected a launch of a ballistic missile by North Korea, which may have flown on a irregular trajectory.

The nuclear-armed North’s ballistic missile programme is banned by United Nations Security Council resolutions, but in recent years Pyongyang has forged ahead in developing missiles of all ranges.

In March, North Korea fired multiple ballistic missiles while blaming the South Korean and US militaries for conducting drills it calls dangerous and provocative.

North Korea has also exported short-range ballistic missiles, among other weapons, to Russia for use in the war in Ukraine, according to US and allied intelligence agencies as well as independent researchers.

Pyongyang and Moscow have denied the weapons trade, although North Korean troops have been deployed to fight on the frontlines in Russia’s Kursk region.