With pressures growing daily to shrink the defense budget and to increase spending for the environment, Senate Armed Services Committee Chairman Sam Nunn (D-Ga.) has taken the obvious step of attempting a merger.

He proposes that the departments of Defense and Energy (whose nuclear weapons responsibilities make it part of the defense establishment), their associated contractors and research centers, the national laboratories and parts of the intelligence agencies be organized into a formidable new program of environmental research and development in what Nunn revealingly calls the "likely growth industry of the next 20 years."

Nunn's initiative is both welcome and troubling. Because his judgment on military affairs is universally respected, Nunn's recognition that environmental trends "pose an increasing threat to our national security" gives new credibility to what others have been asserting for some time, namely that the traditional definition of national security no longer reflects global realities. On the other hand, the new program suggests that the defense establishment hopes to cash in on environmental concerns with funding and tasks that should instead be aggressively shifted to the civilian commercial sector. The net result could be to slow both the shrinkage of the defense budget and the development of environmentally beneficial technologies.

Parts of the Nunn proposal are unexceptionable. The defense establishment has reams of data that now sit uselessly in vast government warehouses. Ships and submarines have measured ocean temperature and the thickness of Arctic ice for decades, information that would be immensely valuable in understanding global warming. Satellites track the progress of tropical deforestation and other changes in land use. Catalogued and analyzed, just this existing data would be a treasure trove for environmental science. In the future, military platforms, from satellites to submarines, can combine purposeful environmental data gathering with their routine operations, producing large benefits for minimal extra cost.

It also makes good sense for Department of Defense and the Department of Energy to work on improving methods for environmental cleanup, since both agencies have made a huge environmental mess with toxic, radioactive and hazardous wastes. The Defense Department especially can also use its enormous procurement budget to good effect by buying new energy efficiency technologies, substitutes for ozone-depleting chlorofluorocarbons and in general becoming a model environmental citizen.

Beyond this, the Nunn proposal gets onto dangerous ground. The hope that "converting part of the defense establishment's technological know-how from defense to environmental protection can produce a competitive advantage in world markets for U.S. industries" is misplaced. What it amounts to is giving a new mission to the national laboratories and defense contractors who no longer have enough to do. The hitch is that the national security establishment is likely to perform many of the new tasks poorly and at the highest possible cost. It is unlikely that it will be able to produce any commercial technologies that will compete well in the marketplace.

The national laboratories, for example, were established to provide the secrecy needed for nuclear weapons development. Nothing could be less suited to developing competitive civilian technologies. For more subtle reasons of corporate culture and personal inclination, as well as training and experience, defense contractors are unlikely to be good choices for doing much of the work that needs to be done. Their aim has been engineering feasibility, not cost, practicality, ease of use, high materials efficiency, low environmental impact and the other considerations it takes to serve millions of customers rather than one.

Defense now accounts for 70 percent of all public R&D funds. That compares with a global average of 25 percent, and to 12 percent and 4 percent for West Germany and Japan, respectively. Therein lies the root of the problem. If the United States is to boost its economic competitiveness, the enormously disproportionate share of such funds that has been allocated to the military sector must come way down. That, in turn, means a painful transition for scientific and engineering talent and for firms now supported by defense funds. Attempting to sidestep these inevitable dislocations by funneling money through the same recipients for a new job is not the answer.

Proponents argue that if environmental technology development is not funded through the defense budget, it will not get done at all. Certainly in the past the United States has been wary of any concerted planning and investment except for military purposes. Presumably, though, this is one of many post-Cold War adjustments we must squarely face. Budget stringencies make it more likely that defense cuts would be used for deficit reduction than for a new program, but that too is the sort of strategic choice the system should at least strive for. A more cogent argument is that the economic restructuring that accompanies large defense cuts cannot proceed as fast as the recent changes in military threat. If this is true, there may be value in adopting elements of the Nunn program for a strictly defined transitional period.

Global environmental trends do indeed pose a new kind of security threat, but this does not make them amenable to the old kind of security solution. Better to build public support for the notion that new needs demand a new approach to public investment. The writer is vice president of the World Resources Institute.