South Korea says North Korea has fired three short-range missiles into the East Sea, also known as the Sea of Japan.
The South's Defense Ministry says it detected two launches Saturday morning, followed by another in the afternoon.
Ministry spokesman Kim Min-seok says the North's intent was not clear. He says South Korea's military is watching for any additional launches and "possible provocations."
Japan's Kyodo news service reported a Japanese official confirmed the launches and said the missiles did not fall into Japanese waters.
The development comes during a period of tentative diplomacy aimed at easing tensions. Earlier this year, Pyongyang threatened nuclear strikes on South Korea and the U.S. in light of annual U.S.-South Korean military drills and U.N. sanctions imposed on the North after its third nuclear test in February.
About two months ago, North Korea fired off two short-range missiles into the sea off its east coast. Pyongyang routinely conducts such exercises in an effort to improve its arsenal.