North Korea fired four ballistic missiles Monday, three of which landed in Japanese waters, Japanese Prime Minister Shinzo Abe said.
"North Korea today fired four ballistic missiles almost simultaneously and they flew some 1,000 kilometers," Abe said in parliament. "Three of them landed in our country's Exclusive Economic Zone (EEZ)."
Japanese officials described the launches as a grave threat and said they lodged "strong protests" with nuclear-armed North Korea.
"The launches are clearly in violation of Security Council resolutions. It is an extremely dangerous action," Abe said during lawmaker questions in parliament.
The South Korean military officials said "multiple ballistic missiles" were launched from the Tongchang-ri region near the North's border with China. They did not specify the number of missiles.
The move comes as South Korea and the United States are holding their joint military exercises, which Pyongyang sees as preparations for an invasion. The exercises usually draw condemnation and retribution from Pyongyang.
During last year's drills, North Korea fired multiple short to medium range missiles and announced it could place nuclear warheads on its weapons.