North Korea fired what were believed to be four short-range missiles into waters off its east coast yesterday, South Korean defence officials said.
The action appeared to be a protest at annual US-South Korean military exercises that Pyongyang calls a rehearsal for invasion.
The launch was not expected to raise tensions, as North Korea routinely tests short-range missiles and has recently sought better ties with South Korea in what outside analysts say is an attempt to win badly needed foreign investment and aid. The rival Koreas this month held their first reunions in more than three years of families divided by the Korean war.
The projectiles fired were believed to be missiles with a range of more than 200 kilometres, South Korean Defence Ministry officials said.
The officials said they were trying to learn exactly what the North launched, and that the South had bolstered its cross-border monitoring.
Yonhap news agency, citing an unidentified military official, reported the North Korean projectiles were suspected to be Scud missiles or an upgraded version of its newly developed surface-to-ship KN-02 missiles.
Kim Yong-hyun, a professor of North Korean studies at Seoul's Dongguk University, said their launch would not be a prelude to provocation.
He said the North appeared to have intended to protest at the South Korean-US military drills that began on Monday, or to grab international attention as there had been little progress over a push to resume disarmament-for-aid talks.
"It's mainly about sending a message - about the drills and also its anger over the recent UN rights report," Kim said.
A United Nations panel earlier this month recommended the North Korean regime be referred to the International Criminal Court for crimes against humanity in its political prison camps.
Last year, North Korea reacted furiously to the same military drills by issuing a torrent of fiery rhetoric and threats to launch nuclear missiles against Seoul and Washington. Those drills came after North Korea conducted its third nuclear test.
North Korea has not issued any harsh rhetoric against the current drills since their start. Pyongyang earlier threatened to scrap the family reunions in anger over the drills, but later allowed them to proceed after high-level talks with Seoul.
South Korea on Monday offered to send vaccines and disinfectants to the North after the country recently reported its first outbreak of foot-and-mouth disease since April 2011.
- Officials from the Japanese and North Korean Red Cross would hold talks next week on the return of the remains of Japanese nationals from North Korea.
Japanese national broadcaster NHK said the talks would be held in Shenyang in northeastern China, but Atsuhiko Hata of the Japanese Red Cross said the site had yet to be finalised.
Additional reporting by Reuters