Pentagon officials have developed a new plan to enable the U.S. landbased intercontinental ballistic missile system to survive increasingly accurate missiles.
The plan, which the Joint Chiefs of Staff are understood to be viewing favorably, is also designed to conform with limits on nuclear launchers that U.S. and Soviet negotiators have tentatively agreed upon in the curent strategic arms limitation talks.
"This is a whole new wrinkle," said one knowledgeable official yesterday, "and everybody seems to be leaning towards it."
The plan envisions the construction of several hundred concrete holes in the vicinity of the present U.S. missile fields scattered through the upper Midwest and West.
The missile, which would be the bigger and more accurate MX, would be trucked from hole to hole with its own launching equipment on a vehicle that would be visible to Soviet spy satellites. Once the vehicle reached one of the concrete-lined holes, it could slide the missile and its launcher in and move on.
The holes would be constructed in fields allowing a ratio of 10 holes for each missiles, requiring the Soviets to target each hole if they wanted a capability for destroying the entire force.
Soviet targeters, according to the theory of the new plan, could never be sure of destroying enough U.S. land-based missiles in a surprise attack without the risk of an unacceptable retaliatory strike.
The plan is clearly designed to appeal to at least three constituencies vital to the approval of a strategic arms limitation agreement: the Soviets, who strongly favor a verifiable limit on nuclear delivery vehicles; Senate nuclear hawks, who want a new and survivable land-based missile system for the 1980s, and, finally, the White House, which wants a strategic arms treaty that the Senate will approve.
One of the major remaining issue's to be negotiated with the Soviet Union is language governing new missile development in both countries. The other significant roadblocks concern the Soviet Backfire bomber and the American cruise missile.
Proponents of the plan have suggested that there would be means of on-the-ground as well as satellite verification by Soviet or neutral observers.
Under the proposal the concrete covers over the missile holes could be slid back on occasion to reassure the Soviets that no launching equipment was inside them. Another possibility would be to permit on-the-ground random inspection of the missile holes.
The rationale would be to assure the Soviet that the number of missiles would conform to agreed-upon limits. But, as in the proverbial shell game, the Soviet targeters would not know where the missiles are located.
Since it is missile launchers that are counted against the negotiated SALT limits, the empty holes stripped of any launchers presumably would be outside the agreed-upon limits.
One of the attractions that has won favorable ratings for the new plan is that it would cost about half of the $40 billion price tag of an alternative system for deploying the MX blockbuster missile in tunnels. Another advantage, advocates say, is that it could be adapted immediately to the existing force of Minuteman missiles while the MX is being built.
MX has been kept on the nuclear drawing boards pending a solution of what might be the best system for deploying it. It is not expected to be ready for deployment until the mid-1980s.
Carter administration officials have said they hope to negotiate a strategic arms limitation agreement by the end of 1978. Secretary of State Cyrus R. Vance will seek to regain the momentum of the negotiations in meetings on July 12 and 13 in Geneva with Soviet Foreign Minister Andrei Gromyko.
The approval being expressed within the Pentagon for the new proposal suggests that the United States has achieved technological means to overcome the drawbacks previously associated with a mobile deployment system-inability to penetrate dense Soviet cloud cover as well as thickly forested terrain.
Most of the U.S. launch sites are in areas where the weather is predominantly clear and the land visible to Soviet spy satellites.