President Regan's frustrating and protracted search for a solution to the problem of ICBM vulnerability has been doomed from the beginning. The vulnerability problem cannot be solved until there is a SALT limit on the Soviet nuclear threat.

So the president's proposals, announced Friday, for immediate solutions- stuffing 100 "super-hardened" silos with MX missiles -or future solutions-such as an ABM defense of the silos-are not solutions at all. They will not work in the face of an unlimited Soviet force. In short, there is no practical, workable answer to ICBM vulnerability without a SALT treaty.

The Regan adminstration inherited the Carter administration's plan for a mobile MX. This involved placing 200 missiles in 4,600 shelters-enough to counter a treat of 6,00 Soviet counter-silo warheads, roughly the size permitted under the then-pending SALT II treaty. The Reagon administration faced the reality that, without SALT limits, the Soviets could increase their threat to about 10,000 to 15,000 warheads, enough to overwhelm the planned MX force.

The Reagan administration could have proposed countering the larger threat by shuttling more MX missiles among more shelters. We could have have matched our ability to dig holes in the ground against the Soviets' ability to arm their missiles with more warheads. But the Reagon adminstration knew that a greatly expanded MX would not be politically palatable, even if it were technically or economically feasible.

Faced iwth political opposition in the West, the administrationfor the few weeks considered a samller deployment-100 MX missiles in 1,000 shelters. But it was again confronted with the reality that this limited proposal wouldn't work. It could be overwhelmed by a Soviet threat unconstrained by SALT limits.

Driven by frustrations in seeking a solution that doesn't exist without SALT, the adminstration reached perhaps the most dangerous decision it could, By placing the new, larger missiles in silos believed to be vulnerable, we make them even more attractive targets, and we make ourselves more, not less, vulnerable. A nuclear confrontation in the late 1980s could find both the Soviets and us with ICBMS that could appear mutually vulnerable. This could put a hair trigger on nuclear war; either side might be tempted to use its missiles to avoid losing them. So the administration could lead us toward, not away from, nuclear war.

The adminstration admits the silo-based MX missile will be, in a few years, as vulnerable as the Minuteman missiles are now-even if the silos are hardened further. It has therefore proposed an array of potential solutions to make the missiles survivable in the future. Unfortunately, none of these solutions will work if we don't also, simultaneously, negotiate treaty limits with the Soviets.

The alternative that will receive the most attention is defending the silo-based MX with an anti-ballistic missile system. This would lead us down a dangerous and blind alley. Even if we could build a modern ABM capable of intercepting a limited threat, the Soviets could overwhelm it as well with a launcher and warhead buildup if there are no SALT constraints.

To counter such a unconstrained buildup with a larger ABM would mean substantially revising or abrogating the 1972 ABM treaty. This would free the Soviets to expand their own ABM systems. While we could defeat a Soviet ABM, some Soviets and Americans might doubt we could. We would then face doubts about whether our missiles could penetrate Soviet defenses, as well as doubts about whether they could survive a Soviet attack.

We must not give up the AMB treaty's limits on the Soviet defensive threat for the same reason we should immediately seek a negotiated limit on the Soviet offensive threat. Both enhance our nation's security.

The administration also proposes developing a specially designed plane in which the missiles could be deployed. However, the number of aircraft and MX missiles we would build, the number of air bases we would maintain, the percentage of aircraft kept airborne to ensure survivabilty-all would soar unmanageably in the face of an unlimited Soviet threat.

Other proposals by themselves ar similarly inadequate. Without SALT, in this case, and generally, we can deploy any weapon, develop and technology, spend any amount of money and our children and theirs will still be insecure.