North and South Korea are still technically at war anyway after their 1950-53 civil conflict ended with the armistice, not a treaty.
North Korea conducted a third nuclear weapons test in February in breach of U.N. sanctions and despite warnings from China, its one major diplomatic ally.
Despite the tide of hostile rhetoric from Pyongyang, it has kept a joint economic zone with the South open as it generates $2 billion a year in trade from the venture, money the impoverished state can ill-afford to lose.
North Korea will celebrate the anniversary of the birth of its founding father, Kim Il-sung, on April 15. The current ruler is Kim Jong-un, his 30-year old grandson.
While the North has an armoury of Soviet-era Scud missiles that can hit South Korea, its longer-range missiles remain untested.
Independent assessments of its missile strike force suggest that it may have the theoretical capacity to hit U.S. bases in Japan and Guam, but the North has not tested these missiles.
North Korea shelled a South Korean island in 2010 and is charged with the sinking of a South Korean naval vessel in the same year. Pyongyang denies it sank the ship.