North Korea said Monday it must bolster its nuclear capability in a "newly developed way" to cope with what it sees as hostile U.S. policy and military threats amid tensions over the deadly sinking of a South Korean warship.
Separately, the North's military accused the U.S. and South Korea of bringing heavy weapons to the Korean border village of Panmunjom and vowed to take "strong military countermeasures" if they aren't withdrawn.
An international investigation concluded last month that North Korea torpedoed the warship Cheonan near the tense Korean sea border. North Korea flatly denies the allegation and has warned any punishment would trigger war. Forty-six South Korean sailors died in the sinking.
"The recent disturbing development on the Korean peninsula underscores the need for (North Korea) to bolster its nuclear deterrent in a newly developed way to cope with the U.S. persistent hostile policy toward (the North) and military threat toward it," the North's Foreign Ministry said in a statement.
The statement, carried by the official Korean Central News Agency, did not elaborate how North Korea would strengthen its nuclear capability. But analysts said it was threatening to manufacture bombs based on newer programs, such as uranium-enrichment or nuclear fusion, as international criticism of North Korea mounts over the sinking.
"North Korea is applying pressure on the U.S. by saying it can have additional nuclear capability," said Koh Yu-hwan at Seoul's Dongguk University.
North Korea said last year it was in the final stages of enriching uranium, a process that could give it an easier, second way to make nuclear bombs, in addition to its existing plutonium-based program. In May, North Korea claimed its scientists succeeded in creating a nuclear fusion reaction — technology necessary to manufacture a hydrogen bomb.
North Korea cites the threat of a nuclear attack from the U.S. as the main reason behind its drive to build atomic weapons, though the U.S. has repeatedly said it has no intention of attacking. Pyongyang — which is believed to have enough weaponized plutonium for at least a half-dozen weapons — conducted underground nuclear tests in 2006 and 2009, drawing international condemnation and U.N. sanctions.
The North's warning came after top world leaders at a G-8 meeting near Toronto over the weekend criticized its nuclear program. The leaders also condemned the attack that led to the sinking of the Cheonan, citing an independent report that found North Korea was responsible.
Also Monday, the North's military said, "the fully armed U.S. imperialist aggression troops and the South Korean puppet army" deployed "various types of heavy weapons" to Panmunjom village.
It was "an indication that they are set to perpetrate a military provocation (at) any moment," the North's military said in a protest message sent to the U.S. command in Seoul on Monday, according to a separate KCNA dispatch.
The U.S. military said it was checking the North Korean statement. South Korea's Joint Chiefs of Staff said it cannot confirm the reported weapons introduction.
The 1950-53 Korean War ended in an armistice rather than a peace treaty. The United States stations about 28,500 troops in South Korea as a deterrent against the North.
The American-run U.N. Command — which oversees the armistice — said in a statement Monday it has proposed military talks with North Korea to discuss the warship sinking but the North declined it. On Sunday, Pyongyang accused the U.S. of trying to meddle in inter-Korean affairs under the name of the U.N.
Backed by the U.S. and other countries, South Korea has taken its own punitive measures against North Korea, including trade restrictions. The North reacted angrily, declaring it was cutting off ties with Seoul and threatening to attack.
South Korea has taken the issue to the U.N. Security Council to seek punishment for North Korea.
© Copyright 2015 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.