The Air Force's MX missile system, already facing stiff opposition from the western states where it would be deployed, came under attack today from the head of the U.S. Arms Control Association, who said that the $33 billion missile system won't work.

Dr. Herbert Scoville Jr. said that the annual meeting of the American Association for the Advancement of Science that the missile system will not only fail to assure the United States of the second-strike nuclear capability that it is supposed to provide, but may actually encourage a preemptive nuclear attack by the Soviet Union.

"Instead of being a deterrent, it will provide an incentive for a Soviet launch-on-warning strategy, which would greatly increase the risk of accidental nuclear war," he said.

For years, the Air Force has argued that the nation's ballistic missiles are vulnerable to any nuclear first-strike by the Soviets. The Air Force contends that the MX missiles remaining after any initial Soviet strike had hit empty shelters would provide the second-punch deterrent necessary to prevent the attack in the first place.

But Scoville says that the mere existence of the MX system is likely to encourage that first move by the Soviets. "We cannot be naive enough to think that if the Soviets launched their nuclear warheads first, they would conveniently leave any of them sitting in the silos to be wiped out by our counterattack."