SALT II is fighting to stay alive. Although the nuclear arms control treaty was never ratified, the United States and the Soviet Union are abiding by its ceilings on multiple-warhead missiles. Now the Reagan administration is signaling that it may decide to exceed the pact limits on grounds the Soviets are violating the accord.
Treaty supporters in Congress and the arms control community warn that such an action would remove the one vehicle providing stability in the superpower nuclear balance. Without it, they stress, both sides will be speeding up the nuclear arms race -- and the Soviets will have the advantage.
Three coming dates provide the framework for crucial decisions that President Reagan must make:
By June 1 the administration is required to submit a report to Congress on the military implications of US compliance with SALT II.
In September the USS Alaska, the seventh US Trident submarine, will begin sea trials, putting the US in violation of the treaty limits of 1,200 multiwarhead (MIRVed) missiles on land and at sea.
In December the unratified SALT II pact expires.
The President is carefully keeping his options open. But he stated in Europe recently that if the Soviets are violating the treaty, ``there is no need for us to continue'' honoring it. He went on to say this was a decision to be made down the road and the US would respond in due course.
Under SALT II, each side is permitted 1,200 MIRVed intercontinental missiles on land and at sea. The Trident sub carries 24 missiles, as against 16 on the Poseidon. Deployment of the next Trident would put the US 14 missiles over the 1,200-missile limit unless a Poseidon were dismantled. The US at present has 1,190 MIRVed missiles.
White House officials stress that US policy is not one of unilaterally complying with SALT II. Rather it is a policy not to undercut the treaty as long as the Soviets show similar restraint.
But the administration has deemed the Soviets to be violating the treaty by developing two new ICBMs instead of one and by coding missile test data to a greater degree than the treaty permits. They would like to find some way of continuing the treaty without fully complying with the letter of it.
Because the Soviets are seen as violating the accord, officials say, the basic decision for the President is whether to continue abiding by the pact and show a restraint, which the Soviets are not reciprocating, or to continue general compliance but not show full restraint.
There are deep divisions within the administration as the matter undergoes intensive review. At one end of the spectrum are hard-line opponents within the civilian Pentagon, led by Assistant Defense Secretary Richard N. Perle, who argue that the treaty should be allowed to lapse. At the other end are supporters, including many military officers, who believe that a breakout from the treaty would be self-defeating, giving the Soviets the benefit.
In the middle are many others who are uncertain what to do in the face of alleged Soviet violations.
``That's a very heavily engaged subject now and . . . lots of people are looking at it from all angles,'' says Edward L. Rowny, a special adviser to the President on arms control. ``It's an extremely involved problem.''
Administration officials say it is doubtful that a decision will made by June 1. But it will have to be made by September, assuming the Trident is on schedule.
One proposal being considered to avoid violation of the treaty is to mothball a Poseidon submarine when the USS Alaska puts out to sea and dismantle its firing tubes. This would legally violate the pact, but, in the words of one US official, be ``politically and diplomatically more fungible,'' or acceptable.
Another option is to delay sea trials of the USS Alaska -- on grounds of, say, technical problems. The SALT II issue then would not impinge on a Reagan-Gorbachev summit meeting, if one does take place in the fall. Critics of a SALT breakout warn that such a move would gratuitously strain the atmosphere of a summit meeting.
Arms control experts note that there is no operational reason to retire a Poseidon. ``So this would be a deliberate destruction of a good operational system to stay within the limit,'' says an official at the Arms Control Association. ``But if you begin to unravel the quantitative restraints, who will be able to take advantage of that? You'd have to conclude that the Soviets have better capabilities to exploit.''
Four senators -- Dale Bumpers (D) of Arkansas, Patrick J. Leahy (D) of Vermont, John H. Chafee (R) of Rhode Island, and John R. Heinz (R) of Pennsylvania -- who recently wrote President Reagan urging continued compliance with SALT II made the same argument. They noted that the Soviets now have 818 ICBM launchers with multiple warheads, just under the 820 limit for land-based missiles. The US has only 550 MIRVed land-based missiles.
If the US breaks out of the 1,200 limit, the Soviets are well positioned to violate the 820 limit because they are about ready to deploy the MIRVed SS-24 (the new missile permitted under SALT II). Also, the Soviets could add thousands more warheads to their SS-18 ICBMs. And they could avoid dismantling hundreds of SS-11s as they deploy SS-25s, missiles that the US considers a violation of SALT II.
Besides spurring the deployment of more missiles and warheads on both sides, the senators said, a US breakout from the treaty would cause strains in the NATO alliance and damage the atmosphere as the Dutch decide (in November) whether or not to deploy cruise missiles. The West Europeans generally support the no-undercut policy.
Administration officials also are sensitive to the fact that a US SALT breakout would put the Soviets in a more advantageous position. ``The Soviet building program with respect to missile construction is so great that there is no way we want to get into a race with them on numbers of missiles,'' a White House official says.