North Korea has announced it will sever all ties and communication with the South in retaliation for what it calls a smear campaign over the sinking of a South Korean warship in March.
US Secretary of State Hillary Clinton has arrived in Seoul for talks on the escalating row.
An international investigation has found that Pyongyang fired the torpedo which sank the warship, killing 46 sailors.
South Korea has called on the UN Security Council to impose new sanctions on its neighbor.
Pyongyang has also threatened military action against the South, claiming Seoul's navy trespassed into the disputed waters of the Yellow Sea.
An international investigation found that Pyongyang fired the torpedo which sank the warship, killing 46 sailors.Michel Chossudovsky, the head of the Center for Research on Globalization, an independent Canadian think tank, argues that North Korea is more prey than a predator.
“North Korea is portrayed in the international media as a threat to global security, but there is absolutely no evidence to that effect. On the other hand, North Korea is the only country in the world that has lost up to a quarter of its population in recent history [during the Korean War, when the North Korean population was wiped out by US bombings],” Chossudovsky told RT.