How can we stop bank robbers in their tracks? A politician might suggest doubling the number of guards to calm the public and intimidate would-be thieves. A policeman might recommend installing more video cameras, combination locks and metal gates. A judge might advocate increasing legal penalties for armed robbery.

These approaches, though well meaning, would remain tedious, expensive and arbitrary; no matter how great our resolve, we simply can’t anticipate every threat to every bank in the country. Fortunately, there is another solution, inspired by Willie Sutton’s purported explanation of why he robbed banks: “Because that’s where the money is.” If banks no longer distributed hard currency and became mere financial-service centers-turning over the payment function to smart debit cards-bank robberies would stop.

So far, society prefers to absorb the cost of bank robberies rather than move to a cash-free economy. Yet Sutton’s practical observation offers an important clue to addressing a challenge that our society does judge intolerable: terrorism. The most effective way to address terrorism is neither better offense nor better defense. Rather, it is to take away the ball. Creatively eliminate the tools of terrorism, and you go a long way toward eliminating the terrorist.

How do we, for example, stop airplanes from doubling as aerial suicide bombs? Answer: sponsor more research on fuel additives that prevent jet fuel from catching fire outside an engine. NASA, among other groups, has investigated such “fuel-inerting” and “antimisting” technologies, but progress to date is modest due to inadequate funding and industry support.

How do we stop fertilizer from doubling as a bomb-making ingredient, as it did in Oklahoma City? Eliminate the need for conventional fertilizer by developing crops capable of fixing nitrogen from the air. Plants such as soybeans have evolved bacteria-filled nitrogen-fixing nodules in their roots. Genetic engineering and conventional plant breeding techniques could transfer this important characteristic to other crops.

How do we keep our water supply safe from bioterrorists? A water purifier in every building and every home. New technologies combining ozone, ultraviolet radiation and mechanical and carbon filtration can eliminate every possible impurity, from volatile organic chemicals to viruses.

Such approaches not only make tactical sense, they make strong economic sense as well. Fuels that fail to catch fire outside an engine would reduce the fatality rates and material costs of all air and auto accidents. New nitrogen-fixing crops would reduce the amount of energy required to manufacture petroleum-based fertilizers and ship them to the farm. They would also reduce our dependence on foreign oil, while helping spread peace and stability by lowering the cost of large-scale agriculture in developing countries. More effective technologies for on-location water purification could lower the cost of recycling suburban “gray” waste water and provide an inexpensive source of potable water for many of the world’s poor.

None of this activity would, of course, do much to lessen the short-term hit to our economy from the September 11 attacks. According to the National Governors’ Association and other agencies, the antiterrorist campaign’s first year alone will drain tens of billions from the already faltering U.S. economy. Every dollar spent fighting this war is a stunning blow to world productivity and could well be echoed in higher inflation rates, followed by a lowered standard of living. The events of September 11 were, indeed, attacks on a way of life, and their effectiveness must be judged in terms of not only lost lives, but also lost livelihoods.

We must also begin to think creatively, therefore, about ways to prevent this short-term cycle from turning into a longer-term spiral. The war on our current terrorist enemies could stretch indefinitely into the future. Moreover, new enemies, aware as never before of our society’s vulnerabilities, may well attempt to exploit them in the years ahead. That is where a coordinated campaign to combine terrorism prevention with economic growth becomes crucial.

We have ample precedent for such a campaign. In the last 20 years, the U.S. government has come to recognize that many military technologies are too expensive to build independently and are best developed in tandem with civilian applications. Often called “dual-use” technologies, they have included the integrated circuit, which was first used for military applications such as Minuteman missile guidance and now powers everything from kids’ video games to supercomputers to military situation rooms. Reliable civilian golf carts, to cite another example, carry landscapers around parks in the United States; yet slightly repurposed, they serve as low-cost battlefield ambulances in Afghanistan.

Dual-use technologies offer dual economies in the war on terrorism. They reduce costs by increasing production volume. But just as important, they expand the base of designers, testers and users, thus greatly expanding the number of smart people evaluating and improving them. Cheaper products and more brainpower-a powerful one-two punch!

Yet the dual-use doctrine alone doesn’t give us sufficient leverage to defeat terrorism. The problem is that many dual military-civilian technologies can still be misused or circumvented. To return to the bank heist comparison: banks that adopt consumer video cameras for surveillance or use radio-controlled model airplanes to track getaway cars could still be robbed and innocent bystanders killed. As Sutton said, it’s not the bank, it’s the money. Less-flammable fuels and nitrogen-fixing plants are therefore more accurately described as “deny-use” technologies-the next step in the evolution of dual use.

Taken to its logical conclusion, deny-use should extend to our weapons systems themselves. A common scenario for a terrorist attack, for example, involves the firing of a shoulder-launched Stinger missile against Air Force One or the Capitol. Our ability to stop this kind of attack is very limited, depending almost entirely on intervention through counterintelligence methods.

Yet think for a moment about how terrorists acquire those weapons. The United States produces them and gives them to friendly powers. As the years pass, they often find their way into unfriendly hands. How can the deny-use doctrine neutralize this threat? To give just one example, we could design our weapons to degrade, so that after three to five years the Stinger’s rocket fuel and explosives would be inoperable.

Degradable weaponry offers other potential advantages as well. Short-lived mines, for example, would pose a far smaller threat to farmers and other civilians than the millions of unexploded mines that lurk under yesterday’s battlefields. And from a business standpoint, degradable weapons could be part of a military-commercial partnership focused on “design-for-recycling” techniques much like the ones now used by the European auto industry. Saving lives, saving money and saving the environment in one program-now that’s the American way.

In the coming R&D war on terrorism, Congress, the U.S. Defense Advanced Research Projects Agency and other organizations should give full attention to promoting antiterrorist technologies that follow two fundamental guidelines. First, these technologies should be designed to deny terrorists tools and targets. Second, they should not be an economic burden on society; they must have a broad and substantial impact on commerce and productivity.

We will never track down every terrorist in the world, nor stop the insane and malevolent from imposing their warped visions on others. But we can deny them targets worthy of attack-including our underlying economic prosperity.