Many of Japan's political and intellectual leaders remain committed to nuclear power even as Japanese public opinion has turned sharply against it. One argument in favor rarely gets a public airing: Japan needs to maintain its technical ability to make nuclear bombs. "I don't think Japan needs to possess nuclear weapons, but it's important to maintain our commercial reactors because it would allow us to produce a nuclear warhead in a short amount of time," Shigeru Ishiba, a former defense minister, said in an interview in a recent edition of Sapio, a right-leaning twice-monthly magazine. "It's a tacit nuclear deterrent," added Mr. Ishiba, an influential parliament member who made similar remarks on a prime time television news show in August while serving as policy chief of Japan's main opposition party. Instead of sparking an outcry, his remarks seem to have stimulated further consideration of their merits. The Yomiuri newspaper, Japan's largest-circulation daily, urged the government to stay the course on nuclear power in an editorial last month, stressing that the country's stockpile of plutonium gives it diplomatic leverage."As Japan has worked to strengthen the Nuclear Nonproliferation Treaty regime through the peaceful use of nuclear power, the nation is permitted to use plutonium that can be used as material for nuclear weapons. In fact, this also functions diplomatically as a potential nuclear deterrent." the paper said. Those holding the view appear to remain in the minority. The Japanese government says it is committed to its self-imposed Three Non-Nuclear Principles, a 1967 policy banning the production, possession and presence of nuclear weapons in Japan. Tokyo also signed and ratified the Non-Profileration of Nuclear Weapons Treaty in the 1970s. Japan was the first country without nuclear weapons to sign the Comprehensive Nuclear Test Ban Treaty in 1996. "We have absolutely no plans to change the existing policy based on the Three Non-Nuclear Principles, so that's the way we'll deal with things going forward," Minister of Defense Yasuo Ichikawa said in an interview last month. Japan has the technology—including its H-2B rocket, shown launched in January from the island of Tanegashima—to develop and deliver nuclear weapons. Most establishment figures who continue to back nuclear energy stress other reasons for support. Prime Minister Yoshihiko Noda has endorsed keeping atomic power as a part of the country's energy mix, at least for several more decades, until alternative sources are developed. That stems from concern about electricity shortages, which could lead to blackouts and stifle economic growth. Abandoning nuclear power would also increase Japan's dependence on carbon dioxide-producing fossil fuels with volatile prices, according to the conventional wisdom in Kasumigaseki, Tokyo's bureaucratic hub. Recent public-opinion polls show the Japanese public turning against nuclear energy after the March Fukushima Daiichi nuclear accident. But even when support was high for commercial atomic use, surveys have shown the Japanese people were overwhelmingly against introducing nuclear weapons. Some 72% of respondents in a 2009 poll conducted by the Mainichi newspaper, a nationwide daily, said they supported keeping the Three Non-Nuclear Principles in tact, while only 24% wanted them revised or scrapped to allow the introduction of nuclear weapons. Japan has long had a "nuclear allergy" due to its status as the only country against which nuclear weapons were used, in 1945 attacks on Hiroshima and Nagasaki. Even though Japan has shown no sign of adopting nuclear weapons, many experts say Tokyo has the necessary raw materials—thanks to a nuclear-fuel reprocessing program that produces enriched uranium and plutonium—and the means of delivery in the form of government-subsidized commercial rockets, which they say are technically indistinguishable from ballistic missiles. It takes just 10 tons of civilian-grade plutonium to be converted into weapons-grade material for up to 1,000 nuclear weapons, according to a 1998 Council of Foreign Relations paper by physicist Richard Garwin, a U.S. Los Alamos National Laboratory consultant from 1950 to 1993. As of the end of 2010, Japan had 30.1 tons of fissile plutonium, according to a Japanese Cabinet Office report submitted on Sept. 20 to the Japanese Atomic Energy Commission. Security experts point to some recent developments that have highlighted Japan's advanced technology, which could also be used to deliver a warhead. They note that Japan passed a law in 2008 allowing military applications in its outer-space programs, ending a 40-year ban limiting space development to commercial or research programs only. They also cite the Hayabusa government test satellite, which successfully landed on an asteroid before returning to Earth in June 2010. It employed the same type of atmospheric re-entry technology needed to guide ballistic missiles. Hayabusa's success as a civilian program is a point of pride for most Japanese, and the technicians who worked on it are considered heroes by many. A big-budget movie currently playing in Japanese theaters, one of three motion pictures featuring the Hayabusa program, showcases the scientists' efforts to advance space science on behalf of mankind but makes no mention of any possible military applications. Yet national-security hawks say that aspect is hiding in plain sight. "That's the behind-the-scenes reason Japan decided to develop Hayabusa," says Toshiyuki Shikata, a former lieutenant general in Japan's military and currently a Teikyo University professor and Tokyo Metropolitan Government adviser. "It sent a quiet message that Japan's ballistic missile capability is credible." Most security experts say it makes little strategic sense for Japan to remove itself from the U.S. nuclear umbrella, the cornerstone of the U.S.-Japan defense alliance, which provides an ample deterrent. Undermining that blanket American-provided nuclear protection could erode the entire bilateral security relationship, they say. "Japan can develop nuclear weapons very quickly if it decided to, but it would be very difficult for political leaders to go down that path," said Kevin Maher, an independent consultant and former 30-year veteran Japan hand at the U.S. State Department. "We've never had any concern about the Japanese government building a nuclear weapon," he said, citing issues such as cost, public opinion and defense strategy. Other experts on Japan say the issue is more complex. Japan is surrounded by nuclear armed states such as China, North Korea and Russia. "The Japanese government has also hedged a great deal on the issue of nuclear weapons, which is what raises concerns abroad," said Saadia Pekkanen, an adjunct professor at the University of Washington, who co-authored a 2010 book on Japanese defense technology. "Japan is credible as a latent nuclear power, and should be taken seriously as such by its rivals in the region," she said.