Deeply concerned over last week’s North Korean missile tests, the Japanese government is reportedly studying its own constitution, to determine if a pre-emptive strike against Pyongyang’s missile sites would violate Japanese law, which bars the use of force in settling international disuptes.

Rattled by North Korea’s recent launch of seven missiles, several Japanese officials have openly discussed measures for improving the nation’s defense, including creation of a legal framework that would allow pre-emptive attacks against DPRK missile facilities. As Chief Cabinet Secretary Shinzo Abe recently observed:

If we accept that there is no other option to prevent an attack … there is the view that attacking the launch base of the guided missiles is within the constitutional right of self-defense. We need to deepen discussion,” he observed.

Obviously, such talk will generate renewed concern among Japan’s neighbors, who suffered greatly at the hands of Tokyo’s military forces during World War II. But such fears are exaggerated, at the very least. The Japan of today bears no resemblance to the militaristic society of the 1930s and 40s. Japan’s post-war constitution, partially drafted by General Douglas MacArthur’s JAG staff, contains strict limitations on the nation’s military, including the prohibition on offensive attacks.

These legal measures, coupled with Japan’s own war experiences, have created a strong pacifist streak within Japanese society that is reflected in its military. Tokyo has mounted only one troop deployment since World War II, a small, support mission to Iraq that will end in the coming months. The deployment was largely unpopular with segments of the Japanese public, which viewed it as inconsistent with the post-war constitution. Japanese military units are referred to as “self-defense” forces, and their equipment and doctrine reflects a true defensive orientation. Development of even a modest offensive capability would require several years, an investment of billions of dollars–and convincing the Japanese public to support such a plan.

Still, Japan’s mere willingness to examine potential “offensive options” underscores Tokyo’s growing frustration with the North Korean missile tests, and a perceived lack of support from its neighbors in the region. China and Russia are unwilling to back draft UN resolutions on the missile issue, and South Korea (in a nod to domestic politics) has accused Tokyo of inflaming the situation.

That, of course, leaves the U.S. in a difficult position. The Bush Administration has been trying to develop a regional consensus on the issue, and Tokyo’s support has been both valued and welcome. But increasingly, the U.S. and Japan find themselves isolated on the issue, with little tangible support from Moscow, Beijing or Seoul. If North Korea continues its missile and WMD programs, Japan has every right to expand its military forces and consider potential offensive options–a prospect that will clearly infuriate the Chinese, South Koreans and Russians. In that scenario, what would President Bush (or more likely, his successor) do? Undermine a critical alliance with Japan, or risk antagonizing key trading partners in the region?

While Japan weighs its military options for the future, the missile episode has (if nothing else) provided a dramatic wake-up call for Tokyo. Facing a growing missile threat from North Korea (and China’s own, massive military build-up), Japan has come to the sobering realization that it lives in an increasingly dangerous part of the world, and responsibility for its defense begins not in Washington, but in Tokyo. The Chinese, Russians and South Koreans won’t be happy, but Japan (and the U.S.) will be more secure if Tokyo improves its military capabilites to deal with regional threats.