North Korea is cancelling a non-aggression pact with South Korea and reiterating past threats in anger over a UN Security Council vote to impose more sanctions for its third nuclear test.
The statement the North issued today comes after the council levelled tough new sanctions targeting its economy and leadership.
North Korea has already threatened a pre-emptive nuclear strike on the US.
North Korea says it will retaliate with “crushing strikes” if enemies intrude into its territory. It also says it is voiding past nuclear disarmament statements between North and South Korea.
It previously said it was cancelling a hotline with the US and the armistice that ended the Korean War in 1953.
German Foreign Minister Guido Westerwelle has urged China to use its influence over North Korea to persuade Pyongyang to halt its "threats and provocations", which risked exacerbating North Korea's isolation and poverty.
He welcomed China's support for the United Nations sanctions on North Korea, but added: "It is also Beijing's responsibility to tell the powers in North Korea that with these renewed threats and provocations they have gone too far."
"I urge China to use its influence to persuade Pyongyang that sabre-rattling, war rhetoric, provocations and infringements of international law must come to an end.”