North Korea has ramped up the level of its threats by telling the UN Security Council that South Korea and the United States have created a "nuclear war situation" in the region.
In a statement released by its foreign ministry on Tuesday, Pyongyang then said it had entered the final stage of a full-scale war to protect its sovereignty from the U.S.
The ministry said Washington would be burnt to death by the fire it has set.
In response to the North's threat that it was ready to strike the U.S., the State Department said the regime would achieve nothing with such provocative behavior.
The Pentagon said the U.S. was taking North Korea's aggressive rhetoric seriously.