North Korea fired multiple short-range ballistic missiles on Wednesday that landed in the sea off its east coast, South Korea and Japan said, days after Pyongyang unveiled a uranium enrichment facility and vowed to beef up its nuclear arsenal.

The missiles lifted off from Kaechon, north of the capital Pyongyang, at around 6:50 a.m. (2150 GMT Tuesday) in a northeast direction, South Korea's Joint Chiefs of Staff (JCS) said, without specifying how many were fired.

"Our military is maintaining full readiness posture while strengthening surveillance and vigilance in preparation for additional launches and closely sharing information with the U.S. and Japan side," it said in a statement.

About 30 minutes after the first missile notice, Japan's coast guard said North Korea fired another ballistic missile, noting the projectiles appeared to have fallen.

The U.S. Indo-Pacific Command said on X that it was aware of the launches and consulting closely with Seoul and Tokyo.

The North fired several short-range ballistic missiles last Thursday, the first such launch in more than two months, which it later described as a test of a new 600mm multiple launch rocket system.

South Korea's JCS has said the launch might have been to test the weapons for export to Russia, amid intensifying military cooperation between the two countries.

The United States, South Korea and Ukraine, among other countries, have accused Pyongyang of supplying rockets and missiles to Moscow for use in the war in Ukraine, in return for economic and other military assistance.

North Korean Foreign Minister Choe Son Hui, who is visiting Russia this week to attend conferences, met her counterpart Sergei Lavrov in Moscow on Tuesday and discussed ways to promote bilateral ties, the Russian foreign ministry said on its website.

Wednesday's missile launches also came days after the isolated country for the first time showed images of centrifuges that produce fuel for its nuclear bombs, as leader Kim Jong Un visited a uranium enrichment facility and called for more weapons-grade material to boost the arsenal.

  - Reuters