AKIPRESS.COM - North Korea fired four ballistic missiles into the sea off Japan's northwest coast early on Monday, South Korean and Japanese officials said, days after the reclusive state promised retaliation over U.S.-South Korea military drills it sees as a preparation for war.

South Korea's military said the missiles were unlikely to have been intercontinental ballistic missiles (ICBM) which could reach the United States, but flew on average 1,000 km (600 miles) and reached a height of 260 km, reported Reuters.

Some of the missiles landed in waters as close as 300 km to Japan's northwest coast, Japan's Defence Minister Tomomi Inada said in Tokyo.

"The launches are clearly in violation of (UN) Security Council resolutions. It is an extremely dangerous action," Japanese Prime Minister Shinzo Abe said in parliament, adding "strong protests" had been lodged with nuclear-armed North Korea.

South Korea's acting President Hwang Kyo-ahn condemned the launches as a direct challenge to the international community and said the country would swiftly deploy a U.S. anti-missile defense in the face of angry objections from China.

The missiles were launched from the Tongchang-ri region near the North's border with China, South Korean military spokesman Roh Jae-cheon told a briefing. It was too early to say what the relatively low altitude indicated about the types of missiles, he added.

"South Korea and the United States are conducting a close-up analysis, regarding further information," South Korea's Office of Joint Chiefs of Staff said in a statement.

The U.S. military said it detected and tracked what it assessed was a North Korean missile launch, but it did not pose a threat to North America.