(ATTN: UPDATES with more info throughout)
SEOUL, March 7 (Yonhap) -- One day after North Korea fired four ballistic missiles, its state-run news agency said Tuesday the country has conducted a missile launch exercise targeting U.S. military bases in Japan.
The drill was conducted by Hwasong artillery units of its Strategic Force of the Korean People's Army, "tasked to strike the bases of the U.S. imperialist aggression forces in Japan," the Korean Central News Agency (KNCA) said.
The report did not disclose when the drill was carried out, but it was apparently referring to its launch of four ballistic missiles a day earlier. The North's missile tests are usually announced by its state media the next day.
The launch of the missiles that flew about 1,000 kilometers was seen as a response to the on-going joint military exercise between Seoul and Washington, which North Korea denounces as a war rehearsal against the North. Three out of the missiles landed in Japan's exclusive economic zone.
The KCNA said North Korean leader Kim Jong-un, who supervised the exercise, ordered the units to be fully ready to open fire to annihilate the enemies once the ruling Workers' Party of Korea gives the order.
The leader voiced expectations that artillerymen under the unit should carry out their mission and duty as a "credible nuclear force" of the party, it added.
The latest test came amid intensified pressure against North Korea following its provocation in February and the killing of the half brother of the country's leader in Malaysia.
Pyongyang test-fired a new intermediate ballistic missile on Feb. 12, the first missile launch since U.S. President Donald Trump took office in January.
The South Korean military said that the missile appeared to be developed with technology from submarine-launched ballistic missiles.
North Korea is banned from testing any ballistic missile technology under a set of U.N. resolutions. Pyongyang carried out two nuclear tests last year alone and launched ballistic missiles in defiance of international condemnation.