Seoul: North Korean leader Kim Jong Un supervised Monday's test launches of four missiles, the country's official news agency reported on Tuesday, stepping up threats against Washington as U.S. troops conduct joint military exercises with South Korea.
North Korea fired four ballistic missiles into the sea off Japan's northwest, angering South Korea and Japan, days after it promised retaliation over the military drills which it sees as preparation for war.
U.S. President Donald Trump and Japanese Prime Minister Shinzo Abe discussed North Korea's missile launches during a phone call on Tuesday.
"Japan and the U.S. confirmed that the latest North Korean missile launches were clearly against U.N. resolutions and a clear provocation against the regional and international community," Abe told reporters. "(North Korea's) threat has entered a new phase."
U.S. Defence Secretary Jim Mattis and Japanese Defense Minister Tomomi Inada also discussed the missile launches in a telephone call on Monday, the Pentagon said.
An "important contact" between South Korea and the United States would be made on Tuesday, South Korea's foreign minister Yun Byung-se told members of the ruling party.
The missile test were undertaken by an army unit commissioned with attacking U.S. military bases in Japan, the North's official KCNA news agency said.
"In the hearts of artillerymen... there was burning desire to mercilessly retaliate against the warmongers going ahead with their joint war exercises," KCNA said.
"He (Kim) ordered the KPA Strategic Force to keep highly alert as required by the grim situation in which an actual war may break out any time, and get fully ready to promptly move, take positions and strike so that it can open fire to annihilate the enemies."
The missiles North Korea fired on Monday were unlikely to have been intercontinental ballistic missiles (ICBM), South Korea said, which can reach the United States. They flew on average 1,000 km (620 miles) and reached an altitude of 260 km (160 miles).
Some landed as close as 300 km (190 miles) from Japan's northwest coast, Japan's Defence Minister said earlier.
The United States and Japan have requested a United Nations Security Council meeting on the launches, which will likely be scheduled for Wednesday, diplomats said.
Condemning the launches as further "provocative behaviour," the White House said earlier the United States was taking steps to enhance defense against ballistic missiles, including deployment of a Terminal High Altitude Area Defense (THAAD) battery in South Korea.
The U.S. anti- missile defense system to be deployed this year has irritated China and led to a diplomatic standoff between China and South Korea.
Chinese authorities have closed nearly two dozen retail stores of South Korea's Lotte Group that approved a land swap with the country's military last week to allow it to install the system.
South Korea needed THAAD for its national security despite "China's restrictions in various ways", foreign minister Yun said on Tuesday.