The Korean Central News Agency (KCNA) said, in an English dispatch, "(Kim) convened an urgent operation meeting on the Korean People's Army's Strategic Rocket Force's performance of duty for firepower strike at the Supreme Command at 00:30 Friday.
"He finally signed the plan on technical preparations of strategic rockets, ordering them to be on standby to fire so that they may strike any time the U.S. mainland, its military bases in the operational theaters in the Pacific, including Hawaii and Guam, and those in south Korea," the report said.
It added that Kim pointed out that by letting B-2s make sorties over the South, the U.S. once again showed its hostile intent against the North and claimed Washington's provocation has entered a reckless level, "going beyond the phase of threat and blackmail."
The KCNA said that Kim viewed the B-2 bombing drills as more than simple demonstration of force in reaction to the tough stance by North Korea, but an ultimatum that Washington will ignite a nuclear war at any cost.
"Kim declared the revolutionary armed forces of the DPRK would react to the U.S. nuclear blackmail with merciless nuclear attack, and war of aggression with an all-out war of justice (of its own)," the KCNA said. The DPRK stands for the Democratic People's Republic of Korea, the North's official name.
Meanwhile, the swift reporting of a middle of the night emergency meeting of senior commanders is unusual and may reflect the level of intimidation felt by Pyongyang with the appearance of the B-2s over South Korea.
The U.S. Air Force's nuclear-capable stealth bombers carried out their bombing drill over the Korean Peninsula, hitting Jik Islet off Gunsan with bombs on Thursday. The move is seen as a clear message of strong warning to Pyongyang, which has recently threatened a pre-emptive nuclear attack on the U.S. and South Korea.
The North ratcheted up tension by launching a long-range rocket late last year and by detonating its third nuclear device on Feb. 12, in the face of strong opposition from the international community.
The planes took off from Whiteman Air Force Base in Missouri on Wednesday and flew over 10,000 kilometers using airborne refueling to reach South Korea the following day. The bombers can each carry up to 23 tons or various guided bombs and are designed to penetrate heavily defended air space to strike key targets such as command and control facilities without being detected by radar.
South Korea views the North's bluster as a response to the bombing exercise, an official said.
"A B-2 stealth strategic bomber conducted a bombing exercise over the Korean Peninsula yesterday," the presidential official said. "Though this bombing exercise is part of routine drills between South Korea and the U.S., we take First Chairman Kim's order as a step to respond to this (exercise)."
The official also said the government is carefully handling the situation.