SEOUL (Reuters) - North Korea said on Saturday it would begin a “sacred war” against the United States and South Korea at “any time necessary” based on its nuclear deterrent, in response to “reckless” military exercises by the allies.

North Korea has driven tensions on the Korean peninsula to new heights after the South accused the North of sinking one of its warships in March, killing 46, and took steps to boost its defense including massive military drills with the United States.

Pyongyang customarily voiced shrill anger in the past when the allies conducted exercises, but U.S. officials said further provocations are possible, especially as the North tries to build political momentum for succession of power to Kim Jong-il’s son.

U.S. and South Korean militaries begin large-scale naval and aerial drills on Sunday with a nuclear-powered aircraft carrier taking part and they have additional exercises planned in August.

“The army and people of the DPRK will start a retaliatory sacred war of their own style based on nuclear deterrent any time necessary in order to counter the U.S. imperialists and the South Korean puppet forces deliberately pushing the situation to the brink of a war,” the North’s National Defense Commission said.

DPRK is short for Democratic People’s Republic of Korea.

“All these war maneuvers are nothing but outright provocations aimed to stifle the DPRK by force of arms to all intents and purposes,” the powerful commission said in a statement carried by the North’s official KCNA news agency.

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It again denied that the country was behind the sinking of South Korea’s corvette Cheonan, and said the planned military drills were “as reckless an act as waking up a sleeping tiger.”

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Washington brushed off the latest threat and said it had no interest in getting into a war of words. “What we need from North Korea is fewer provocative words and more constructive action,” State Department spokesman P.J. Crowley said.

The North escaped rebuke by the U.N. Security Council, which condemned the attack in a statement early in July without directly blaming the Pyongyang government.

An official speaking on the sidelines of a multilateral Asian forum in Vietnam last week said the U.S.-South Korean drills also violated the spirit of the U.N. statement, which called for dialogue to ease tensions.

North Korea has called for the resumption of six-party nuclear disarmament talks that it had boycotted since late 2008, a move analysts said was an attempt to put the Cheonan incident behind and win lucrative aid through a deal with the South, the United States, Japan, Russia and China.

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North Korea again on Saturday said that it was prepared to engage in talks with regional powers and take strong physical actions against any sanctions.

“If the U.S. puts sword to us, we will put sword to them, which is how we counteract. We are ready for both talks and wars. We are not the one who would be surprised by military threats or sanctions,” North Korean foreign ministry spokesperson said in a statement carried by KCNA.

The United States and South Korea have rejected the call and said Pyongyang must first prove that it is genuinely interested in change by first apologizing for sinking the Cheonan.

Following talks in Seoul on Wednesday, U.S. Secretary of State Hillary Clinton announced fresh sanctions on North Korea aimed at freezing its assets earned from illicit activities including arms trade and cut off the flow of cash to its leaders.