South Korea's defense ministry says North Korea has launched four short-range missiles off its east coast.
A spokesman for the ministry gave no other details about the launch, which occurred late Thursday. Pyongyang's government has not commented.
It is not uncommon for North Korea to test-fire short-range missiles. Such tests are believed to partly serve as political messages to the South.
The latest launch comes as Seoul and Washington conduct large-scale joint military exercises, which the North views as an unacceptable provocation.
Both sides are on heightened alert during the drills. Following a South Korean military exercise in 2010, North Korea shelled a South Korean island, killing four people.
The launch also comes just days after North and South Korea resumed family reunions between those separated by the 1950s Korean War. It was the first time such reunions have been held since 2010, raising cautious hopes of improved inter-Korean ties.
The two Koreas remain in a technical state of war following the conflict, which ended in a truce and not a formal peace treaty.