TOKYO – The United States is willing to use its full military might to defend Japan in light of North Korea’s nuclear test, Secretary of State Condoleezza Rice said yesterday as she sought to assure Asian countries there is no need to jump into a nuclear arms race.

At her side, Rice’s Japanese counterpart drew a firm line against his nation developing a nuclear bomb.

The top U.S. diplomat said she reaffirmed President Bush’s pledge, made hours after North Korea’s Oct. 9 underground test blast, “that the United States has the will and the capability to meet the full range – and I underscore the full range – of its deterrent and security commitments to Japan.”

Rice spoke following discussions with Japanese Foreign Minister Taro Aso, the first stop on her crisis mission to respond to the threat posed by the North.

Signs continued yesterday that North Korea might be readying for a second nuclear test that could be carried out as soon as this week, while Rice is in Asia.

There were reports North Korea had told China it was ready to conduct up to three more nuclear tests. But at the State Department in Washington, spokesman Tom Casey said, “We certainly haven’t received any information from them, from the Chinese, that they’ve been told by Pyongyang that another test is imminent.”

U.S. government officials, who spoke on condition of anonymity because of the sensitive situation, said there wasn’t evidence to suggest another nuclear test in North Korea was hours or even days away.

But given the underground nature of the testing, officials said, it could happen with little or no warning. Analysts have been monitoring the movement of trucks and VIP buses around test sites as well as military communications, media activity and official travel.