The United States is sending 24 B-1 and B-52 bombers to the island of Guam in the Pacific to deter any aggression by Pyongyang in case of a war in Iraq.
US officials said the deployment was a prudent measure to maintain peace in Korea but they said it was not prompted by the interception of an unarmed US Air Force reconnaissance jet by North Korean fighters in international air space over the Sea of Japan on Sunday.
"These movements are not aggressive in nature," said Mr Jeff Davis, a Pentagon spokesman. "Deploying these additional forces is a prudent measure to bolster our defensive posture and as a deterrent."
In Sunday's incident, four North Korean fighters intercepted the RC-135 surveillance plane about 240 kilometres off the North Korean coast and came within 15 metres of the US jet while shadowing it, the Pentagon said.
The United States denounced the intercept as reckless but said it still saw a diplomatic, not military solution to the stand-off with the communist state.