Rice said Japan and China "don't lack contacts" through regional fora, and recently agreed to settle a border dispute in the South China Sea.

"It may sound like a minor matter, but it's not," Rice said referring to the joint efforts on demarcation, which she said "would be a very big step forward, actually, for them."

Asked if Japan's likely constitutional reform would lead the country to seek nuclear weapons under the new prime minister, Rice, in a transcript of the interview provided by the State Department, said she was unconcerned.

"I do not think we're headed in that direction with Japan. I think there are a lot of self-regulating reasons for Japan to remain non-nuclear," she said, stressing that Japan was "very concerned about the North Korean (nuclear) issue and its proliferation activities."

One of the reasons the six-party talks "was so important for controlling the nuclear ambitions of North Korea because it has Japan at the table with China, with the United States, with Russia (and South Korea), and I think then forestalls any further nuclearization of the region," she added.

Rice said "the Japanese will have to decide" what their new constitution should say, adding that the United States has been strengthening US-Japan defense cooperation "quite dramatically over the last couple of years."

Outspoken conservative Shinzo Abe on Tuesday became Japan's youngest prime minister and the first leader born after World War II, replacing veteran Junichiro Koizumi.

The 52-year-old Abe, who has vowed to rewrite the US-imposed 1947 pacifist constitution, on Monday picked Nakagawa to lead the ruling Liberal Democratic Party.

Nakagawa is a fellow conservative but also has close connections to China. He has said he will try to repair relations soured by Koizumi's visits to a controversial war shrine, which is seen as a symbol of Tokyo's militarist past.

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