Few world leaders can pass up the temptation of a nice photo op with the men and women in uniform, and Junichiro Koizumi is no exception. So there was the Japanese prime minister last week, looking his dashing best in bright fall sunshine, as he prepared to commemorate the 50th birthday of his country's postwar military by reviewing a procession of 4,000 soldiers, complete with attack helicopters, heavy tanks and armored personnel carriers. But none of those heavy arms was in evidence as the parade got started; in the lead instead was a phalanx of water trucks--symbols of the Army's devotion to disaster relief.

It was one of those self-effacing moments that the Japanese have come to expect from the Self-Defense Forces, or SDF. Yet, ironically, Koizumi's visit to the troops comes at a moment when Japan's military is on the cusp of some of the most significant changes in recent memory. Koizumi and his political colleagues--many of them members of a generation that doesn't feel unduly burdened by the legacy of the second world war--are laying the groundwork for an overhaul of their country's defense strategy, one that would give the SDF more of an offensive orientation.

What's making the process--which has been maturing steadily since Koizumi took office in 2001--more urgent are rising tensions between Japan and its behemoth neighbor China. The two countries have sparred for years over disputed territory and the unresolved legacy of World War II, but more recently have become economic and energy rivals. China is worried about U.S.-Japan cooperation on missile defense, fearing the technology could be shared with Taipei. A recent incursion into Japanese territorial waters by a Chinese sub has aggravated rising nationalism on both sides. Last Sunday, Koizumi and Chinese President Hu Jintao met at the APEC summit in Santiago, Chile, to soothe feelings--but it's clear that Japan's pre-eminence in East Asia is being challenged by a powerful upstart. North Korea has always worried Tokyo; now the perceived danger from China is upping the ante.

Japan's reaction to the Chinese sub incident was, by Asian standards, forward-leaning: it named the culprit, demanded a public apology--and got one. "For the first time, we're actually pointing out that it's a Chinese sub," says foreign-policy expert Jitsuo Tsuchiyama of Aoyama Gakuin University in Tokyo. "These sorts of things are new in Japanese policy." Not long after the Chinese expressed their "regret" over the incident, Japanese newspapers were bruiting a more proactive possibility: that the Japanese Navy might set up a forward base on a strategically sensitive island in the area to keep an eye on future incursions. (The Japanese Defense Agency has denied the rumor.) "In the past the government was always worried about negative reactions from China," says Masashi Nishihara, president of the National Defense Academy, the elite war college for the Japanese military. "But now the government is bolder. That's a new development. We have to be a little more assertive."

China is not the only problem; the threat of a nuclear-armed North Korea remains. The larger concern is that North Asia is an increasingly unpredictable strategic neighborhood, especially as the United States gradually eases its military footprint in the region. In stark contrast to Europe, where the Great Power rivalries of the cold war have been dissolved into the EU and NATO, Japan and its neighbors are still basically at daggers drawn. "Northeast Asia has no multilateral security architecture, and it's the region that needs one most," says Alan Dupont, of Australia's Lowy Institute, author of a recent report titled "Unsheathing the Samurai Sword: Japan's Changing Security Policy." "You can see how the tensions are rising and the possibility of miscalculations over something relatively minor could easily lead to something much more serious."

The process of changing Japan's military stance to face such threats can seem almost comically painstaking. Talk of revising Article 9--the clause that outlaws aggression and basically denies Japan any real military forces at all--has been going on for years. Now, though, consensus seems to be building that revision in some form is inevitable. Koizumi has spoken of writing an explicit role for the Self-Defense Forces into the Constitution--an idea that seems to be backed by a growing majority of Japanese. Recent proposals for changing the Constitution by a panel inside the ruling Liberal Democrat Party even embrace the hitherto off-limits notion of "collective defense"--meaning that the future role of the Japanese military wouldn't be confined just to defending the homeland but could also, theoretically, encompass combat at the side of allies in far-off theaters. "In Iraq right now, security for our troops is being provided by the Dutch," says Nishihara. "But if the Dutch get into trouble, the Japanese [under the present Constitution] wouldn't be able to help them. Is that a healthy situation?"

Some changes are already underway. Dupont points out that the past year has seen a spurt of parliamentary legislation--mostly unnoticed by the public--that has cleared away "a whole raft of administrative impediments" to the use of the military. Among other innovations still in the works: raising the existing Japan Defense Agency, previously a minor office subordinated directly to the prime minister's office, to the status of an autonomous ministry with a staff to match.

Within the cloistered world of Tokyo's think tanks and policy foundations, the talk is also becoming more hawkish. One widely discussed idea: purchasing Tomahawk cruise missiles from the United States as a way of striking at North Korean ballistic missiles on the launchpad before they can be fired at Japan. It's an option that could be taken up--albeit in veiled language--in a new defense-strategy blueprint that's scheduled to appear in Tokyo in early December, the first of its kind in almost a decade. On the face of things, the proposal might seem reasonable enough; right now Japan doesn't have any weapons of its own that might effectively deter a genuine North Korean threat. But it raises constitutional ramifications: can firing Tomahawks at land targets in North Korea still be construed as "self-defense" if it isn't clear where the missiles are headed? Critics--and they are still legion--fear that adopting first-strike weapons like the Tomahawk could trigger a new regional arms race.

Japanese conservatives don't mind the talk. After hunching passively under the U.S. diplomatic and security umbrella for half a century, they're hailing the new spirit of "realism" in military affairs. "The Japanese used to think that we could rely on international good will," says Kimindo Kusaka, head of the Tokyo Foundation think tank. "Now people have realized that sometimes it's necessary to use power." The shift may be gradual, but it's serious.

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