North Korea fired what appeared to be two short-range ballistic missiles on Monday, the South's military said, weeks after Pyongyang threatened to demonstrate a "new strategic weapon" and its deadline for Washington to offer sanctions relief expired.
The launch was the nuclear-armed North's first for more than three months and came as nuclear negotiations with the United States remain at a standstill.
The two devices were fired eastwards over the sea from the Wonsan area on the east coast and flew 240 kilometres (150 miles) at a maximum altitude of 35 kilometres, the South's Joint Chiefs of Staff said.
They were "believed to be short-range ballistic missiles," a JCS official said. South Korea's security ministers expressed "strong concern" the North was "carrying out actions giving rise to military tensions", the presidential Blue House said.
Japan's defence ministry said there was no indication of anything coming down in its waters or exclusive economic zone, but added: "Recent repeated launches of ballistic and other missiles by North Korea are a serious issue."