North Korea enters 'state of war' with South 30 March 2013 Last updated at 02:33 North Korea has said it is entering a "state of war" with South Korea in its latest escalation of rhetoric against its southern neighbour and the US. A statement promised "stern physical actions" against "any provocative act." North Korea has threatened attacks almost daily after it was sanctioned for a third nuclear test in February. It has also reacted angrily to annual US-South Korean military exercises. However, few think the North would risk a full-blown war. North and South Korea have technically been at war since the armed conflict between them ended in 1953, because an armistice was never turned into a peace treaty. The North carried out its third nuclear test on 12 February, which led to the imposition of fresh sanctions. Many analysts believe that all-out war with South Korea and its ally the United States would be suicidal for Pyongyang, says the BBC's Lucy Williamson in Seoul., But with both sides threatening heavy retaliation, there's a chance of minor incidents escalating, our correspondent adds. Taking threats seriously A North Korean statement released on Saturday said: "From this time on, the North-South relations will be entering the state of war and all issues raised between the North and the South will be handled accordingly." The long-standing situation of the Korean peninsula being neither at peace nor at war is finally over. 30 Mar: North Korea says it is entering a "state of war" with South Korea In Washington Caitlin Hayden, a spokeswoman for the National Security Council, said the US had "seen reports of a new and unconstructive statement from North Korea." "We take these threats seriously and remain in close contact with our South Korean allies," she said. On Thursday, North Korean state media reported leader Kim Jong-un "judged the time has come to settle accounts with the US imperialists." State media in the North showed thousands of soldiers and students at a mass rally in Pyongyang supporting of Kim Jong-un's announcement North Korea's most advanced missiles are thought to be able to reach Alaska, but not the rest of the US mainland. Unilateral action White House spokesman Josh Earnest said the rhetoric only deepened North Korea's isolation. China, North Korea's biggest trading partner, has reiterated its call for all sides to ease tensions. Foreign Ministry spokesman Hong Lei told a daily news conference that "joint efforts" should be made to turn around a "tense situation." Russian Foreign Minister Lavrov went further, voicing concern that "we may simply let the situation slip out of our control and it will slide into a spiral of a vicious circle." "We are concerned that... unilateral action is being taken around North Korea that is increasing military activity," he said. The jointly run Kaesong industrial park is still in operation.