SEOUL, South Korea, Sept 18, (AP): 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 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 north of its capital, Pyongyang, and said they traveled about 400 kilometers (244 miles) while flying toward the northeast. The joint chiefs said it was closely communicating with the United States and Japan while analyzing the launches but didn’t immediately provide further flight 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.

The South Korean joint chiefs condemned the launches as a provocation that "seriously threatens peace and stability on the Korean Peninsula." It said in a statement that South Korean and U.S. militaries were closely monitoring North Korean activities while maintaining a combined defense posture "to respond overwhelmingly to any provocation.” North Korea didn't immediately confirm the launches.

They 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.