This November will mark the 80th anniversary of one of the most disturbing military assessments ever uttered by a western leader. On November 10, 1932 Britain's de facto prime minister Stanley Baldwin said the following in a parliamentary debate about military policy:

I think it is well also for the man in the street to realise that there is no power on earth that can protect him from being bombed. Whatever people may tell him, the bomber will always get through. The only defence is in offence, which means that you have to kill more women and children more quickly than the enemy if you want to save yourselves.

Coming as they did on the eve of Armistice Day and just before the latest futile European disarmament conference, Baldwin's remarks created quite a stir. They captured the widespread fear of how the emerging air weapon might be used in future wars -- a fear that led thousands of people to evacuate Paris and other continental cities during the Czech crisis in 1938. As it turned out, Baldwin was only half right; the invention of radar in the late 1930s greatly reduced the danger of not knowing from whence an air attack might originate. But the advent of ballistic missiles and nuclear weapons restored the power of Baldwin's prophecy, because even with radar there was no way any country could prevent a well-armed adversary from causing untold damage. So western societies spent the second half of the 20th Century protected against nuclear attack mainly by the threat of retaliation.

Nobody talks much today about Baldwin's bleak vision, even though mankind continues to live with the danger of potential nuclear annihilation. But as time goes by, more and more of the security threats we face seem to have the same character of inevitability that the British leader attributed to strategic bombing. Look at what happened to U.S. military vehicles in Iraq. Costly vehicles were destroyed by inexpensive explosive devices, so that the Pentagon had to spend many billions of dollars fielding trucks that could withstand the danger. As my colleague Dan Goure has pointed out, those armored trucks are so unwieldy they are likely to be useless in future conflicts. And now the Army wants to develop a new troop carrier reflecting the lessons of Iraq that will cost $10-17 million per copy. Why does it cost so much? Because a shaped charge only has to penetrate one point on the vehicle to destroy it, so the whole system needs to be elaborately protected. Ten million dollars to guard against a simple explosive device that any country can fabricate. This sounds a lot like the situation that Baldwin described in 1932 -- we can't defend ourselves against the emerging threats posed by imaginative adversaries.

There are plenty of other arenas in which disruptive technologies and tactics are now posing an inexorable challenge to U.S. security. How much time and money did it take Osama bin Laden's ragtag band to mount the 9-11 attacks that ended up costing America thousands of lives and trillions of dollars? How much will we spend over the next decade trying to defend our computer networks against increasingly ubiquitous cyber threats that cost very little to launch but could turn off the lights across America or shut down our financial system? And when the first biological attack hits U.S. soil, how ready will we be to cope with a real rather than metaphorical virus that has been engineered to evade containment and treatment?

Our current military establishment isn't much better equipped for dealing with these kinds of emerging threats than the R.A.F. was in 1932 at coping with German bombers. It's not that we can't imagine defenses, but they are so horrendously expensive relative to the effort demanded of attackers that in the end we might bankrupt ourselves trying to keep up. And it isn't just money that we will lose trying to keep these latter day "bombers" from our shores. We may also have to give up many of our cherished rights. Nobody today is prepared to make that sacrifice because we have barely begun to experience the consequences of what disciplined, innovative adversaries can accomplish with emerging technologies. But that day is coming, and when it arrives we will struggle with the same despair Britons felt as war clouds gathered in the 1930s. Let's hope we are strong enough to make similar sacrifices in defense of our homeland and values.

Loren B. Thompson, Ph.D.