Seoul: North Korea on Friday threatened to "bury in the sea" a US aircraft carrier, as it slammed a three-nation naval drill involving US, South Korean and Japanese warships.
The latest warning from the isolated regime came a day after the United States launched a two-day joint military drill with South Korea and Japan off the southern coast of the Korean peninsula.
The drill involved the nuclear-powered aircraft carrier USS George Washington, guided-missile ships, anti-submarine helicopters and early warning aircraft.
"The war drills show that the US-Japan-South Korea tripartite military alliance has developed into the nuclear war alliance and has become operational in actuality," the North`s Committee for the Peaceful Reunification of Korea said in a statement.
If the three countries launch "a nuclear war while talking about `sign` and `preemptive attack` despite repeated warnings of (North Korea), its revolutionary armed forces will immediately mount counter-attack to bury the aggressors, provocateurs in the sea together with the carrier," it said.
North Korea has repeatedly condemned joint military drills south of the border and threatened counter-attacks that have not materialised.
On Tuesday, North Korea warned the United States of a "horrible disaster" over the latest drill and put its troops on alert.
US and South Korean officials have described the drill as a search and rescue exercise to improve readiness for humanitarian disasters.
Seoul and Washington last week agreed a joint strategy to address what they described as the mounting threat of a North Korean nuclear attack after Pyongyang restarted an ageing plutonium reactor.
Analysts have attributed the regime`s recent bellicose rhetoric to its desire to attract the United States` attention and draw it back into dialogue.
The United States and South Korea have long demanded that Pyongyang show commitment to ending its nuclear weapons programme before six-nation talks on disarmament, which have been stalled since December 2008, can resume.
Although the North`s atomic test in February -- its most powerful to date -- sent tensions soaring, the temperature has been lowered in recent months after a series of conciliatory gestures by Pyongyang towards Seoul.
But acute concerns remain over the North`s nuclear programme, with South Korea`s spy agency telling lawmakers on Tuesday that Pyongyang has restarted its ageing Yongbyon reactor.