4 days after, was the fifth and perhaps the most powerful nuclear weapons test in North Korea, the U.S. air force responded with a show of force on Tuesday, showing two powerful, proven in combat B-1 bombers that flew over South Korea.

North Korea said Friday that the test showed that now they have a nuclear warhead that can be mounted on a ballistic missile, and this increases fears for U.S. allies in the region and poses a threat to American bases in South Korea, Japan and GUAM.

"The nuclear test of North Korea is a dangerous escalation and pose an unacceptable threat," said General Vincent K. Brooks in his statement on Tuesday. "The United States have an unwavering obligation to protect allies in the region and to take the necessary steps to do it, including operations as of today."

B-1s have joined US fighters F-16 and F-15 in a low-level overpass Osan Air Base, 40 miles (64 km) South of the capital of South Korea Seoul. "Today's demonstration provides only one example of the full spectrum of military capabilities in the deep resources of this strong Alliance to provide and strengthen extended deterrence," said Brooks.

On the diplomatic front, U.S. special envoy for North Korea sung Kim said Tuesday that the U.S. and South Korea will consider "additional unilateral measures" in response to the latest nuclear test by Pyongyang. Kim also said that Japan could be included in a supplementary initiative.

B-1s that flew over South Korea were transferred to the air force base Andersen on the island of GUAM in August, as part of what US Pacific command calls it a continuous presence.

GUAM is the territory of the United States in the Western part of the Islands of the Pacific ocean, 1,550 miles (2,500 km) East of the Philippines and also about 1,900 miles (3,000 kilometers) from the Korean Peninsula.
sections: Politics, World News, Accidents