For many policymakers, the concept of national security now simply means possessing the capacity for overwhelming destruction. Armchair warriors find such thinking reassuringly straightforward and comforting, a neat and tidy corollary of "Might makes right." It is also pure fantasy.

To define the security of a nation by its ability to destroy ignores the fact that nations are fundamentally land, water, plants, animals, people and human settlements.

A more objective view proves our world is infinitely complex, both ecologically and socially. In such a world the ultimate goal of national security must be to preserve life-support systems -- vibrant local, regional and global ecosystems -- that ensure a safe and healthy environment for sustainable human societies. In short, national security is environmental security.

This is not to say that military capability is unnecessary. Humans will continue to make war as long as there remains greed and ignorance. More importantly, however, as long as human society is riven by economic inequalities (such as access to natural resources) there will be conflict. But these, too, are environmental security issues and require social and political, rather than military, engagement if solutions are to be found.

So if national security is essentially environmental security, what then is the essence of environmental security? The short answer is biological diversity. Biodiversity encompasses all life found on the planet and can be viewed on three levels: genetic, species and ecosystem diversity. All three levels, and the myriad interactions among them, are critical for human survival. And all three are under siege, in Japan and worldwide.

"Living With Nature: The National Biodiversity Strategy of Japan," a 2002 publication by the Nature Conservation Bureau of Japan's Environment Ministry, outlines four reasons why conserving biodiversity is essential. The first is that biodiversity forms the basis for human life.

"Living things are inter-related and inter-connected within the Earth's biosystem. They contribute in various ways, such as absorbing carbon dioxide, stabilizing temperature and humidity, forming soil . . . all of which provide the foundation for human existence," explains the report.

Second, by conserving biodiversity we assure the long-term security of human life. For example, by conserving riverside forests we can protect watershed areas that filter and control runoff, ensuring safe drinking water and preventing erosion and flooding.

The third rationale is that a diverse environment possesses value for human use, supplying industrial materials, medical supplies, fuel and food. "Furthermore, nature, which nourishes diverse wildlife, is a fountainhead of values that enrich human life, such as education, art and recreation," states the report.

Finally, biodiversity provides a basis for cultural enrichment. "Each region's culture has been nurtured by its own biota," explains the booklet. "Diversity in living things and cultures furnishes assets unique to each region and offers a key to successful regional vitalization in the future."

Wonderful in theory, you say, but look at the reality. All around Japan, farmers and major-property owners are selling off bits and pieces of their land to developers so they can pay their bills. Elsewhere, astronomically high inheritance taxes are forcing landowners to cut up their small holdings into even smaller lots. Orchards, forested hillsides, rice fields and fine old homes are being chopped up, literally and figuratively.

Despite a decade-long postbubble slump, public works projects, too, still incessantly devour private and public lands, chipping away at the nation's rich fortress of biodiversity.

A particularly egregious example is the Kenoudo Expressway being constructed outside Tokyo. If ever completed, the Kenoudo will circle 300 km through Saitama, Ibaraki, Chiba, Kanagawa and western Tokyo, primarily Hachioji. Though the plan was first unveiled in the early 80s, citizen opposition and lawsuits have limited the completed portion of the highway to a mere 28.5 km. One key lawsuit is targeting plans to carve two massive tunnels through Mount Takao and several nearby hills in a forested area of Hachioji that is home to one of Japan's highest levels of biodiversity.

In Japan, it is not uncommon for destructive, poorly planned public works projects to languish for decades as groups of tenacious citizens wrangle with ministry bureaucrats, politicians and construction firms. Unfortunately, though, bad ideas do not die a natural death, and the construction juggernaut continues to bulldoze local neighborhoods and unique natural lands in the name of economic stimulus.

Last week, though, another obstacle stood in the path of the Kenoudo construction. According to Kyodo News Service, the Tokyo District Court ordered the Tokyo Metropolitan Government to suspend the forcible expropriation of land in Akiruno City, which neighbors Hachioji. The suspension is temporary, until a related court case is settled, but it is a landmark decision offering hope that the judiciary is finally willing to consider the true costs that ill-conceived public works projects impose on Japan's national security.

One thing that has not changed, however, is the myopia of construction bureaucrats. In a Japan Times article on the court's decision, a senior official at the Land, Infrastructure and Transport Ministry was quoted as saying, "The land affected by the ruling only involves a 370-meter stretch of the [proposed] road."

In fact, the land affected by the ruling stretches 300 km around Tokyo, and from Hokkaido to Okinawa. By ruling that expropriation may not always be justified, the court has opened its doors to claims that homes, livelihoods and biodiversity have values that go far beyond simplistic cost-benefit analyses.

And even if presiding Judge Masayuki Fujiyama is the sole jurist in Japan so far to recognize that people and their environment are the root of national security, and deserving of constitutional protection, he is a start, and that is what is needed.