Old alliances today seek new purposes, old enemies forge new links, every relationship between East and West is being transformed -- ideology, politics, travel and trade. Everything save the nuclear confrontation.

Virtually unchanged since the nadir of the Cold War, the U.S.-Soviet nuclear confrontation persists, notwithstanding the arms control garlands that have been draped over it. Washington and Moscow keep replacing older nuclear systems with new ones -- an enterprise called "modernization." What is being modernized, however, is the equipment, not the strategy. The same old concepts serve to justify the size and capabilities of nuclear forces.

Today -- as in 1980, 1970, 1960 -- America and Russia deploy vast arrays of nuclear arms, assiduously kept ready every minute of every day to destroy the other side. On both sides this potential for unleashing nuclear holocaust remains the standard for judging which new missiles are "required" and which arms reductions would be "acceptable."

Astonishingly, most people regard this situation as unchangeable. They mistake a Cold War artifact for a physical constant of the nuclear age. They believe that by establishing parity between U.S. and Soviet nuclear forces the confrontation will be made stable. Yet future alliance shifts among other nuclear powers could unhinge this parity overnight. While responsible officials now worry that a breakup of the Soviet Union might fracture Moscow's control over its nuclear arms and that many other nations are acquiring nuclear missiles, they do not seek to revise our strategy to take account of these threats.

One could never tell from the recent nuclear arms agreements that U.S.-Soviet relations have dramatically changed. The limitations on nuclear testing that were completed at the recent summit are no more restrictive than what had been agreed to 16 years ago. And the new START, despite its welcome promise of deep reductions, will let both sides retain far more nuclear weapons on their missiles and bombers than they deployed 18 years ago, at the time of the first strategic arms accord. Had President Bush and President Gorbachev been able to begin with a clean slate, surely they would not have decided that each side needed some 10,000 nuclear weapons to aim at the other.

The time is ripe to prepare an alternative strategy for the second half-century of the nuclear age. At the same time, we need to live with the old strategy for a while, because of the obstinate longevity of strategic forces and the uncertain developments in the Soviet Union. The new START can help in this transition, provided we begin to focus on the fundamental questions instead of becoming diverted by the hoary disputes about oversized Soviet missiles, undercounted Soviet bombers and Cold War notions of "stability."

As a first step, we need to realize how badly today's nuclear strategy and forces remain warped by our erstwhile fear of a Warsaw Pact onslaught. To deter Stalin's armies from marching into Western Europe, we designed our hair-triggered nuclear posture so it would threaten a prompt and all-out nuclear response. This design survived from one generation of weaponry to the next and came to afflict, like a harmful gene, successive generations of Soviet forces as well.

To this day, this legacy from the Cold War in Europe keeps Soviet and U.S. nuclear forces ceaselessly poised to launch a sudden apocalyptic attack. The multiple risks inherent in this contraption create a far greater peril of an apocalyptic nuclear war than the possibility of a premeditated "first strike," which our arms control technicians keep worrying about.

How to overcome this Stalinist gridlock?

Gorbachev asserts that the abolition of nuclear weapons must be our long-term goal, and so did, at one time or another, every American president from Harry Truman to Ronald Reagan. For the foreseeable future, abolition is not a practical idea, notwithstanding the recent U.S.-Soviet agreement to abolish chemical weapons, which are even harder to verify than nuclear weapons. Instead, we should seek to extend the 1987 ban on intermediate-range missiles to all intercontinental missile systems, impose restrictions on bombers to diminish fears of surprise attack, strengthen existing international links for verification and accident prevention, and allow the deployment of missile defenses. Missile defenses (more modest than some of the early SDI proposals) would provide insurance against cheating and against countries that retained nuclear missiles.

Yet, missile defenses, a missile ban, further reductions in offensive arms -- all these familiar ideas are only part of the solution. The essence of the alternative strategy is to enable America and Russia to overcome their nuclear confrontation, not to perpetuate it at lower levels. In the next century, American-Russian relations need be no more antagonistic than they were in the 19th century. While a reformed nuclear relationship would, of course, not ensure such a benign development, continuing the present lethal confrontation would surely prevent it. Worse yet, it would burden the world for decades to come with multiple risks of a catastrophic nuclear war.

The writer was undersecretary of defense in the Reagan administration.