Nuclear deterrence - a threat to kill hundreds of thousands or millions of people - is a concept that does not fit into traditional morals. Yet it has worked, preventing catastrophic wars while making people more civilized and cautious. When one pole of nuclear deterrence weakened because of Russia's political decline in the 1990s, the North Atlantic Treaty Organization (NATO) committed aggression against Yugoslavia. Now that Russia has restored its capability, such a move would be unthinkable. After Yugoslavia, there was an unprovoked attack on Iraq.

In a nearly perfect world, Russia and the US would not need large nuclear stockpiles. But cutting nuclear weapons to a bare minimum in the current conditions would give a big advantage to small nuclear powers, which will see their nuclear potential gain near-parity with larger states.

Moreover, reducing nuclear weapons to a minimum might theoretically enhance the usefulness of missile-defense systems and their destabilizing role. And even non-strategic missile-defense systems, the deployment of which might be useful, will be questioned.

If stockpiles of tactical nuclear weapons are reduced, as some US, European, and Russian experts have proposed, the opponents of Russia's ongoing military reform will have even more reason to object to the reconfiguration of the country's conventional armed forces away from confrontation with NATO toward a flexible-response capability vis--vis other threats.

Similarly, if the US withdraws its largely nominal tactical nuclear weapons from Europe, US-Europe strategic ties would weaken. Many Europeans, above all in the new NATO member states, would then demand more protection from the mythical Russian leviathan.

The world community seems to be losing its strategic bearings. Instead of focusing on the real problem, namely the increasingly unstable international order, it is trying to apply Cold War-era concepts of disarmament. At best, these are marginally useful; more often, they are harmful in today's circumstances.

What is most needed nowadays is clear thinking about how to live with an expanding club of nuclear states while keeping the world relatively stable. To this end, the two great nuclear powers need a coordinated deterrence policy towards new nuclear states.

Simultaneously, they should offer guarantees to non-nuclear states that might feel insecure. In the first place, it is necessary to fill the increasing security vacuum in the Middle East. China, the world's rising strategic player, might join this policy.

Arms-control talks are mostly needed for rendering national arsenals more transparent, and for building confidence between the great powers. That is all there is to their usefulness.

So, instead of mimicking Cold War-era treaties, it is necessary to launch an international discussion on the role of military force and nuclear weapons in the world as it is now evolving. We might then eventually recognize that eliminating nuclear weapons is not just a myth, but a harmful myth, and that nuclear weapons are a useful asset that has saved, and may continue to save, humanity from itself.

The author is dean of the School of World Economics and Foreign Affairs at Moscow State University - Higher School of Economics.