Reagan decides to abide by SALT II. But President keeps options open for US response to Soviet violations

SALT II remains intact. After intense debate within the administration and facing extremely strong pressure from the European allies and Congress, President Reagan Monday announced the United States will continue to comply with the unratified second strategic arms limitation treaty.

Mr. Reagan has informed Soviet leader Mikhail Gorbachev of his decision, the White House said.

This means the US will deactivate and disassemble a Poseidon missile submarine to keep the US within the SALT II limits when sea trials of the seventh Trident submarine begin in September.

But in view of alleged Soviet violations of the accord, the President will keep available ``proportionate responses'' as a hedge against the consequences of Soviet actions. Such responses include accelerating development of the one-warhead Midgetman missile in addition to the 10-warhead MX and beefing up command and control facilities.

Reagan's decision indicates that the more moderate forces in his administration, led by US Secretary of State George P. Shultz, have won out over Defense Secretary Caspar W. Weinberger and the hard-liners, who favor scrapping the pact. Clearly the decision has been a politically difficult one for the President, who treads a fine line between wanting not to undermine the arms negotiations in Geneva and yet still satisfy his conservative constituents.

The President's present stance carries some ironies. For years he campaigned against the unratified SALT II as running counter to US national interests and giving the Soviets the ability to build up their strategic nuclear forces. Now there is a growing recognition within the administration that, while the accord is far from ideal as an arms control vehicle, it is better than having no limits at all.

This is the basic position of the NATO allies, who warn that abandonment of SALT II would remove the one instrument now providing some stability in the US-Soviet strategic balance. Administration officials say the NATO pressures mounted greatly over the weekend, as European leaders urged the US not to further burden the nuclear and space arms negotiations under way in Geneva, and strain the atmosphere for a possible Gorbachev-Reagan summit meeting. The Geneva talks already are deadlocked over the President's ``star wars'' program.

``We studied this carefully from all ends and there's no doubt that the Soviets are violating the pact and we have no reason to continue the present policy of restraint,'' says a senior official.

``But because of the strong sentiment of our allies, who argued that we should go the extra mile and because of our own desire to go one step better and put ourselves on a higher plane than they, we went in this direction.''

Under the pact, each side is permitted 1,200 multiple-warhead ballistic missiles on land and at sea. The Trident submarine carries 24 missiles, as against 16 on the Poseidon. So deployment of the next Trident will put the US at 14 missiles over the 1,200-missile limit unless a Poseidon is dismantled. The US now has 1,190 ICBMs.

Defense Secretary Weinberger argued that, inasmuch as the Soviets have not shown restraint in complying with SALT II, the US is under no further obligation to do so and should allow the pact to lapse.

Many in the arms control community and even members of the Joint Chiefs of Staff believe that an American breach of the treaty would be far more advantageous to the Soviets than to the US. This argument apparently weighed heavily in the final decision to comply with the pact.

For instance, the Soviet Union now has 818 ICBMs with multiple wearheads, just under the 820 limit for land-based missiles. The US has only 550 multiple-warhead land-based missiles. So if there is a mutual breakout from the accord, the Soviets could quickly breach the 820 limit, especially because they are ready to deploy the new SS-X-24, the one new missile permitted under SALT II.

Some arms control experts say that -- administration claims to the contrary -- there has been no material Soviet breach of SALT II. Even the encryption of some missile-test data, while bad, has not been crucial to checking USSR missile tests.

``Encryption was done in the face of our not ratifying the treaty,'' says Gerard Smith, who negotiated the SALT I treaty. ``Why should they help us out when we did not ratify the treaty? From their view, there was some flexibility because we can verify the Soviets without having access to all the telemetry.''

The more important measure of compliance, says Mr. Smith, is staying within the limits for land-based and sea-based missiles -- which the Soviets have done.

For all the flaws of the SALT agreements, arms controllers feel they have served a constructive purpose. Since the SALT I agreement was signed in 1972, experts estimate, the Soviets have dismantled 458 operational missiles on land and sea to stay within treaty limits (as against none for the US). This is more than 25 percent of the current US force in numbers and about one-third in terms of throw-weight, say experts.

One option considered in the National Security Council during heated internal debate these past few weeks involved dry-docking a Poseidon submarine but not destroying the missiles. Inasmuch as the US has six months to destroy the Poseidon, a simply dry-docking of the vessel would be technically within the treaty provisions.

The President has also directed the Department of Defense to make a specific review of Soviet actions and uncorrected violations and to identify specific actions the US might take to accelerate or augment its modernization program in response to Soviet violations. Such review would relate to defense activities and budget for 1986, say officials.

SALT II of 1979 (unratified) US alleges that Soviets have coded performance data during missile flight tests to deliberately hinder treaty verification. US says Soviet SS-X-25 missile is a violation because the Soviets have declared the SS-X-24 their one new missile allowed under SALT II. Soviets may have deployed SS-16s at their Plesetsk test site, despite the SALT II ban on production, testing, and deployment of this missile. Soviets allege that the US circumvented SALT II limits by deploying medium-range missiles in Europe. They accuse the US of putting shelters over missile silos to hinder verification. Sea trials later this year of Trident submarine Alaska could push the US over the 1,200 ceiling set for multiple-warhead missile launchers. Deployment of MX missile and development of Midgetman missile could violate treaty, which limits each side to deployment of one new ICBM. Threshold Test Ban Treaty of 1975 (unratified) US says that although no definitive conclusion has been reached, evidence points to ``likely'' Soviet violations of the 150-kiloton limit on explosive yield in underground nuclear tests. Soviets allege unspecified US violations of limit on explosive yield. Anti-Ballistic Missile Treaty of 1972 US alleges that Soviet construction of large phased-array radar near Krasnoyarsk in central Siberia violates limits on location and orientation of such radars. The US is concerned that when all Soviet ABM activities are taken together, it appears that the Soviets are preparing a system to defend their national territory, instead of the very limited deployment the treaty permits. Soviet Union alleges that the US Strategic Defense Initiative, or ``star wars'' program would violate the ABM treaty. Large early-warning radars being built in Georgia, Texas, Greenland, and the United Kingdom also may violate location and orientation limits.