Leading Article: The last Cold War deal

ON reading today that the United States and Russia are poised to sign a second treaty drastically slashing their holdings of strategic nuclear weapons, many people will say: 'So what? Isn't the Cold War over anyway?' After all, they may argue, the two nuclear superpowers now enjoy friendly relations. The Soviet Union has split into its constituent and now often mutually hostile republics. The icy hand of Soviet imperialism has been lifted from Eastern Europe. Today's dangers come in altogether different forms: from ethnic strife in the Balkans, or the proliferation of primitive nuclear and chemical weapons in the Middle East. The long-dreaded possibility of a strategic nuclear strike from the former Soviet Union no longer looms.

Yet the second Strategic Arms Reduction Treaty (Start 2), which Presidents Bush and Yeltsin may sign together this weekend, still deserves to be hailed, like its predecessor of 1991, as 'historic'. The build-up of these weapons of mass destruction was one of the most terrifying and grotesquely wasteful acts of the Cold War. Under Start 1 the two superpowers agreed to reduce them by around a third from a combined total of approximately 23,000 warheads. Start 2 is expected to cut them to around 3,000 apiece by the year 2003.

The importance of the agreement can be gauged by imagining the effect of a failure to achieve it. Suppose that at the last moment Mr Yeltsin had succumbed to pressure from hardline conservative nationalists from the Congress of People's Deputies or the defence establishment who insisted that Russia keep all its land-based missiles. The impact on relations between Russia and the West would have been chilling. When signed and ratified, Start 2 will tie any future Russian leadership into a treaty framework. Meanwhile, it will renew Mr Yeltsin's credit in the West, even if it may anger his conservative opponents who oppose the drastic reduction of Russia's nuclear arsenal. More realistically, the treaty is a reminder that in this field at least, Russia inherits the superpower mantle of the former Soviet Union, and must be treated as an equal by the United States.

This further reduction in the huge 'overkill' capacity of both sides makes the world a potentially safer place. The old nuclear arms race was partly about having enough weapons left to strike back after a pre-emptive attack concentrated on missile sites. The lower the number of available intercontinental weapons, the more feasible it becomes to create a reasonably secure defensive system against them: one objection to the 'Star Wars' concept was that it could be overwhelmed by sheer numbers.

Theoretically, the agreement embraces the three other former Soviet republics that inherited nuclear weapons: Ukraine, Belarus and Kazakhstan. They have undertaken to hand over their warheads and missiles to Moscow and become non-nuclear states by 1998. But the Ukrainian parliament has been delaying the ratification of Start 1, and is likely to adopt the same tactics over Start 2: its leadership is bound to have misgivings about living without nuclear weapons next to a still powerfully nuclear-armed Russia that might have designs upon Ukrainian territory. Such are the worries of the new European order. Start 2 represents, by contrast, another and very welcome landmark in the passing of the old order.