The arrest of Wen Ho Lee, the American scientist accused of selling nuclear secrets to China, caused a national-security fright. (Lee was released last year after pleading guilty to one count of improperly handling classified information). And while there is interest in Robert Hanssen, the FBI’s Russian agent, his story is mostly being reported as a human drama of greed and betrayal. What explains the difference in reaction to the two dramas?

Perhaps Lee had access to more lethal stuff. But Hanssen worked for the Soviets and then the Russians for more than 15 years. He came across extremely sensitive material about American counterintelligence. He may have given the Russians far more pertinent and useful information than Lee was accused of leaking to China.

Perhaps it was because Lee is an Asian-American and Hanssen is white. But while his ethnicity certainly didn’t help Lee, I don’t think racism was behind the rage directed at him. Far more important was the country he was supposedly spying for. Russia is the problem from the past; China the fear of the future.

Tales of spying for Russia have an almost nostalgic air to them, bringing back memories of the cold war and John Le Carre. We know how that story ended. Having watched the Soviet Union’s ignominious collapse and Russia’s struggle to make it in the new world, it’s hard to get scared by Moscow. Been there, done that.

China is another matter. It remains a closed, mysterious political system run by a powerful elite. Revealing little about itself, it allows us to conjure up images of an adversary who is 10 feet tall.

But the reality is that China has a nuclear arsenal of 450 missiles, all tightly controlled. Russia, on the other hand, has an arsenal of 30,000 nukes and enough material for another 70,000–all of it rusting and ready for sale, accidental launch or implosion. It should worry us a whole lot more.

Behind the exaggerated fears about China lies an error that persists in our world view. We assume that the next threat America will face–like the last one–will come from a rising great power with ambitions to spread its global influence. Our next crisis, in this reading, will be a cold-war-style confrontation, except with China playing the role of the Soviet Union.

But the world has changed. In the next decade or two the United States will confront a world of stagnant or self-obsessed great powers like Japan and Germany, failed states like Indonesia and Pakistan and civil wars like those in the Balkans and Congo. Danger now comes not from areas of strength but weakness. The likely problem for the United States is a series of crises in which Russia plays the role of Austria-Hungary, a great power spiraling downward and spreading detritus as it crumbles.

The greatest immediate threat to American physical security remains that of Russia’s “loose nukes.” Russia is now a Third World country. Its per capita GDP (in purchasing-power terms) is equivalent to Guatemala’s. And yet it has an immense nuclear arsenal that it cannot maintain or safeguard in an even remotely adequate manner. Many of it 5,000 tactical nuclear weapons do not have any locking devices on them to prevent unauthorized use. Local commanders could fire–or, far more likely, sell–these weapons without anybody in Moscow knowing, let alone approving. Massive stockpiles of enriched uranium and plutonium–the critical ingredient in a nuclear weapon–are literally lying around in poorly guarded facilities. A small chuck of this stuff could make Osama bin Laden’s day.

Statesmen like Sam Nunn and scholars like Harvard’s Graham Allison have made important suggestions on ways Washington could help Russia control and dispose of parts of this arsenal. But an even more vital part of the struggle against loose nukes is intelligence and counterintelligence. America’s arsenal might deter President Putin from launching a nuclear strike. But deterrence won’t stop the corrupt colonel in Siberia from selling an Iranian terrorist group a few missiles. In an odd sense, the spy-versus-spy game with Russia has become even more vital, because we now need knowledge and control over events that even the Russian government may not have knowledge or control of.

So far we have been lucky not to have faced worse fallout from the Soviet Union’s collapse. But we’re still in the early years of its decline. Most multinational empires died deaths that were slow, painful and bloody.

This is a tough case to make. Because nothing dire has happened as yet, it sounds like scaremongering. Potential catastrophes don’t register anymore.

For Americans, the lesson of the 1990s seems to have been “It will all work out.” If we go to war, only the bad guys die. If the stock market plunges, it will soon bounce back. If the savings rate plummets, foreigners will lend us more cash. The tune for our times is “Don’t Worry, Be Happy,” which the elder George Bush dubbed his campaign song. And look at him. Even though he lost the 1992 election to Bill Clinton, it all worked out. But maybe the rest of us will not be so lucky.