Some Pentagon officials and military officers are urging the administration to seek an extension of some provisions of the unratified SALT II agreement at the Geneva arms control talks next week to provide interim limits on arms until substantial cuts can be negotiated, according to informed sources.
Both nuclear superpowers have pledged not to undercut the 1979 treaty, which is due to expire at the end of this year, but there have been charges on both sides that some provisions of the treaty are being violated.
The United States will have more to lose than the Soviet Union if the treaty limits are allowed to expire with no replacement, these officials argue. This is because the Soviets are ready for mass production of many more new missiles than the United States.
An unrestrained and immediate offensive arms spurt, moreover, would diminish the administration's hopes that deep cuts in offensive weapons and a meeting of minds on defensive weapons could emerge from the new arms negotiations starting next Tuesday.
President Reagan met with the National Security Council yesterday morning to review options for the upcoming negotiations. One official said later a final presidential decision on instructions for the delegation is not expected until Thursday, when Reagan meets with the U.S. negotiators.
At the Capitol, Soviet Politburo member Vladimir V. Shcherbitsky, leader of a parliamentary delegation that arrived here Sunday, told the House Foreign Affairs Committee that the Soviet Union hopes the Geneva talks will make "a major contribution" to removing the threat of nuclear war.
Up to now U.S. preparations for the strategic weapons part of the Geneva negotiations have dealt primarily with updating the most recent U.S. proposals for deep reductions before the last round of U.S.-Soviet talks ended in December 1983.
One Pentagon official said last week that given planned new missile deployments by both sides, "an interim framework" for strategic system limits based on the existing SALT II limits "would be logical as a transition from where we've been to where we are going." But as of yesterday, sources said, no decision on this point has been made.
The Soviets are expected to propose extension of the SALT II limits at Geneva, an informed diplomatic source said last week. He added that Soviet negotiators may argue that the United States should offer to restrain its space-weapons development in return for Moscow's agreement on continuing the SALT II limits.
SALT II permits each nation an overall limit of 2,250 strategic nuclear missiles or bombers and set a sublimit of 1,200 on intercontinental land-based missiles carrying more than one warhead.
According to U.S. data, the Soviet Union already exceeds the overall limits of SALT II because of failure to make reductions in 1981 as called for in the treaty. Soviet deployments of the new single-warhead mobile SS25, expected to begin late this year, will add to the Soviet totals. This missile is to be followed by the 10-warhead SS24, the test phase for which is being completed, with deployment expected to begin in late 1986.
The practice on both sides has been to retire older missiles when deploying new missiles. "It is important for us that they swap these new missiles for old ones," a senior U.S. military officer said, adding that such an exchange would be made only if some kind of limits were in effect. Without it, he said, "they will only add on and expand their lead in warheads."
For its part, the United States will go above the sublimit on multiwarhead missiles if the new Trident submarine, the Alaska, with its 24 missiles is sent on sea trials this September as now scheduled. There is no decision on whether to retire old U.S. missiles to make up for this deployment.
These officials would also like to retain in modified form the SALT II limitation on "new types" of strategic missiles. Each side is now limited to one new type but both are working on two. A possible U.S. proposal is to increase the limit to two new types, with a requirement that one of them be a single-warhead missile.
The United States has charged that the Soviet SS25 is a violation of the new-type rule, but the Soviets maintain it is a permissible modernization of a missile, the SS13.
Meanwhile, the United States is planning a second new type of its own, the Midgetman. Testing is to begin in the late 1980s with deployment scheduled for 1992.
One provision these officials would like to make stricter is the prohibition on encoding of missile test data, or telemetry, when it bears on the verification of the SALT II treaty. In recent months the Soviets have been encoding nearly everything, according to U.S. statements.