N Korea threatens to attack
Seoul - North Korea threatened military action on Wednesday against US and South Korean warships plying the waters near the Koreas' disputed maritime border, raising the spectre of a naval clash just days after the regime's underground nuclear test.
Pyongyang, reacting angrily to Seoul's decision to join an international programme to intercept ships suspected of aiding nuclear proliferation, called the move tantamount to a declaration of war.
"Now that the South Korean puppets were so ridiculous as to join in the said racket and dare declare a war against compatriots," North Korea is "compelled to take a decisive measure", the Committee for the Peaceful Reunification of Korea said in a statement carried by state media.
Seoul's decision comes at a time when "the state of military confrontation is growing acute and there is constant danger of military conflict", the statement warned.
South Korea's military said on Wednesday it was prepared to "respond sternly" to any North Korean provocation.
'Blatant violation' of international law
North Korea's latest belligerence comes as the UN Security Council debates how to punish the regime for testing a nuclear bomb on Monday in what President Barack Obama called a "blatant violation" of international law.
Ambassadors from the five permanent veto-wielding council members - the United States, Russia, China, Britain and France - as well as Japan and South Korea were working out the details of a new resolution.
South Korea, divided from the North by a heavily fortified border, had responded to the nuclear test by joining the Proliferation Security Initiative, a US-led network of nations seeking to stop ships from transporting the materials used in nuclear bombs.
Seoul previously resisted joining the PSI in favour of seeking reconciliation with Pyongyang, but pushed those efforts aside on Monday after the nuclear test in the northeast.
North Korea warned on Wednesday that any attempt to stop, board or inspect its ships would constitute a "grave violation".
The regime also said it could no longer promise the safety of US and South Korean warships and civilian vessels in the waters near the Korea's western maritime border.
"They should bear in mind that the (North) has tremendous military muscle and its own method of strike able to conquer any targets in its vicinity at one stroke or hit the US on the raw, if necessary," it said.
The maritime border has long been a flashpoint between the two Koreas. North Korea disputes the line unilaterally drawn by the United Nations at the end of the Koreas' three-year war in 1953, and has demanded it be redrawn further south.
The truce signed in 1953 and subsequent military agreements call for both sides to refrain from warfare, but doesn't cover the waters off the west coast.
North Korea has used the maritime border dispute to provoke two deadly naval skirmishes - in 1999 and 2002.
On Wednesday, the regime promised "unimaginable and merciless punishment" for anyone daring to challenge its ships.
Pyongyang also reportedly restarted its weapons-grade nuclear plant, South Korean media said.Reprocessing nuclear fuel
The Chosun Ilbo newspaper said US spy satellites detected signs of steam at the North's Yongbyon nuclear complex, an indication it may have started reprocessing nuclear fuel. The report, which could not be confirmed, quoted an unidentified government official. South Korea's Yonhap news agency also carried a similar report.
The move would be a major setback for efforts aimed at getting North Korea to disarm.
North Korea had stopped reprocessing fuel rods as part of an international deal. In 2007, it agreed to disable the Yongbyon reactor in exchange for aid and demolished a cooling tower at the complex.
The North has about 8 000 spent fuel rods which, if reprocessed, could allow it to harvest 13 to six to eight kilograms of plutonium - enough to make at least one nuclear bomb, experts said. North Korea is believed to have enough plutonium for at least a half dozen atomic bombs.
Further racketing up tensions, North Korea test-fired five short-range missiles over the past two days, South Korean officials confirmed.
A North Korean newspaper, Minju Joson, said in commentary on Wednesday that Pyongyang does not fear repercussions for its actions.
"It is a laughable delusion for the United States to think that it can get us to kneel with sanctions," it said. "We've been living under US sanctions for decades, but have firmly safeguarded our ideology and system while moving our achievements forward. The US sanctions policy toward North Korea is like striking a rock with a rotten egg."