North Korea fired what appeared to be about 10 short-range ballistic missiles off its east coast, South Korea's military said.
Japanese Prime Minister Fumio Kishida said North Korea had launched a ballistic missile that apparently landed outside Japan's exclusive economic zone.
The suspected missiles were fired from the Sunan area near its capital Pyongyang at 6.14am (9.14pm Irish time Wednesday) and flew about 350km before plunging into the sea, South Korea's military said in a statement.
South Korea is sharing North Korean missile-related information with US and Japanese officials, it added in the statement.
The launch came after North Korea failed on Monday at its attempt to put a second spy satellite into orbit when a newly developed rocket engine exploded in flight.
After the failure, leader Kim Jong-un pledged never to give up space reconnaissance projects.
A North Korean foreign ministry official condemned UN Secretary-General Antonio Guterres' statement that the attempted launch of another military satellite using ballistic missile technology was against UN Security Council resolutions.
In another launch watched by its neighbours, North Korea sent hundreds of balloons carrying rubbish and excrement across the heavily fortified border to South Korea yesterday, prompting an angry response from Seoul, which said the act was dangerous.
The United States called on North Korea to stop "further unlawful and destabilising acts" after it launched what appeared to be about 10 short-range ballistic missiles.
While condemning the launch, the US Indo-Pacific Command said it was consulting closely with the South Korea, Japan and other regional allies and partners.
