SEOUL, South Korea — North Korea on Wednesday test-fired multiple ballistic missiles toward its eastern seas, the South Korean and Japanese militaries said, adding to its military demonstrations as tensions with Washington and neighbors escalate.

The launches come days after North Korea offered a rare view into a secretive facility built to enrich uranium for nuclear bombs in a significant show of defiance against the United States and as leader Kim Jong Un called for a rapid expansion of his nuclear weapons program.

South Korea’s Joint Chiefs of Staff said it detected North Korea firing multiple short-range ballistic missiles from a region north of its capital, Pyongyang, and said the weapons flew eastward. The joint chiefs said it was closely communicating with the United States and Japan over the launches but didn’t immediately provide more details.

Japan’s defense ministry said it detected at least two launches but didn’t immediately say what types of missiles they were and how far they flew.

Japan’s coast guard said the missiles were believed to have already fallen into waters between the Korean Peninsula and Japan and urged vessels to watch out for falling objects. Japan’s NHK television said the missiles were believed to have landed outside of Japan’s exclusive economic zone.

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Escalating Tensions and Military Demonstrations

The launches followed a previous round of ballistic tests last week as Kim vowed to have his nuclear force fully ready for battle with its rivals.

The North said the launches on Sept. 12 involved its “super-large” 600mm multiple rocket launchers, which it describes as capable of delivering tactical nuclear warheads. Experts say North Korea’s large-sized artillery rockets blur the boundary between artillery systems and ballistic missiles because they can create their own thrust and are guided during delivery.

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Potential Nuclear Test Ahead of U.S. Election

Since 2022, North Korea has ramped up its weapons testing activities to expand and modernize its arsenal of nuclear missiles targeting the U.S. and South Korea. Analysts say North Korea could conduct a nuclear test explosion or long-range missile test ahead of the U.S. presidential election in November with the intent of influencing the outcome and increasing its leverage in future dealings with the new U.S. administration.