North Korea said Tuesday it would carry out the test to win concessions from Washington, but ironically the move also emboldened Japanese hardliners who want to shed some of the pacifism imposed after defeat in World War II.

"I can't reject the possibility that a nuclear deterrent system would be developed in the region," said Yoshinobu Yamamoto, a professor of international politics at Aoyama Gakuin University.

He envisioned in one scenario that Japan may move to create a nuclear deterrent in East Asia through cooperation with the United States, its main ally.

"Even if the North's missiles do not reach the United States, they could easily put Japan in the firing range and destroy it," he said. "By bolstering the US nuclear umbrella and having Japan in between, it's possible to develop the double deterrent system."

Japan is already believed to be capable of assembling nuclear weapons if it makes the political decision. But more realistically, Yamamoto said Japan might let the US military bring nuclear weapons to its bases in the country.

Either move would be a drastic change of policy for Japan, where more than 210,000 people were killed in the 1945 US atomic bombings that flattened Hiroshima and Nagasaki.

New Prime Minister Shinzo Abe has not called for Japan's nuclearization but supports a wider military role including revising the US-written 1947 pacifist constitution.

The rise of Abe -- known for his hawkish stance on North Korea -- shows the growing willingness of policymakers to think in new ways on military issues, analysts said.

"Those hardliners are speaking on Japan's nuclearization without even facing criticism anymore," said Akira Kato, a professor of political science at Obirin University.

Former prime minister Eisaku Sato proposed developing nuclear weapons in the 1960s as China built the bomb. But his position was rejected by the United States, which provides a security umbrella over Japan.

More recently, a magazine this year quoted Foreign Minister Taro Aso as telling US Vice President Dick Cheney that Japan would need atomic weapons if North Korea pursued a nuclear program. Aso's aides denied the report.

Japan already has a de facto military and most Japanese support revising the constitution. But the country is sharply devided on how far to deviate from official pacifism.

A recent study by a US House of Representatives committee on intelligence said that Japan -- and also South Korea and Taiwan -- could be driven to pursue nuclear weapons if North Korea tests an atomic bomb.

An official in South Korea, which like China remains wary of Japan over its militarist past, also warned that North Korea could push Japan into developing nuclear weapons.

"That may provide an excuse for Japan's nuclear armament, which in turn will cause repercussions from China and Russia and lead to a change in the overall balance of power," Vice Foreign Minister Yu Myung-Hwan said Wednesday.

But many analysts are still skeptical that nuclear weapons would be on Japan's political agenda anytime soon.

Japan in 1998 slapped sanctions on India and Pakistan after their shock nuclear tests.

"Some people will start discussing the matter actively," said Masao Okonogi, Keio University professor of North Korean studies. "But I don't think their argument would become the mainstreem."

"Japan is a member of nuclear Non-Proliferation Treaty," he said. "Would Tokyo leave the treaty and do the same thing as Pyongyang?"

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