Settling One Issue May Help the Other : Nail down nuclear arms control pact and pave the way for progress on a chemical one

It’s time for Washington and Moscow to close the book on arms agreements to end the Cold War and join forces against the spread of chemical and biological weapons.

Nobody can yet say for certain why Iraq did not use chemical weapons during the Gulf War. But the fact that they were around is warning enough that such grisly warheads may be the future weapons of choice. Ten to 20 mostly Third World countries have chemical weapons in stock.

Moscow and Washington must take the lead. Gen. Mikhail A. Moiseyev, the Soviet chief of staff, will fly to Washington next week to talk with U.S. officials at the Pentagon and State Department about another arms control subject entirely. That’s START, a nearly completed agreement to cut long-range nuclear missile forces in both countries rather than merely limiting their expansion, as two earlier treaties did. Under the treaty, the Soviets would cut their land-based intercontinental missile force by something more than half. The Arms Control Assn., a private Washington-based advocate for arms treaties, estimates that would mean 3,500 or more U.S. warheads could survive any nuclear first strike, a retaliatory force ample enough to deter any nation pondering a surprise attack.

This, in addition to verification plans that will all but keep Soviet nuclear arms factories in constant sight, seems to outweigh technical differences about how to count the warheads on some missiles.

Moscow has sent a tough bargainer. Gen. Moiseyev has been among the Soviet leaders to complain most loudly that President Mikhail S. Gorbachev gave away too much in the treaty on Conventional Forces in Europe. Ironically, that’s why he could be the ideal negotiator to clear away obstacles to slashing East and West air and ground forces in Europe.

Moreover, Presidents Bush and Gorbachev agreed last year to start destroying chemical weapons. But the real problem is outside Europe. (Allied casualties from chemical attack during World War I made “gas” so repugnant that it has not been used on the Continent since.)

Banning chemical weapons will be far harder than manufacturing them. The difference between the formula for a tolerable pesticide and a deadly nerve gas often is razor thin. An innocent plant is easily converted to making chemical warheads, as experience in Libya and Iraq has shown.

Monitoring chemical plants to guarantee that they remain innocent will be a complex task. The sooner the major powers focus on it, the better. Getting the strategic-arms treaty out of the way will only add to positive superpower momentum.