Treaty critics aim beyond ratification. Conservative objections to the INF pact could frame the debate over cuts in long-range nuclear missiles.

Critics have come out swinging in the opening rounds of Senate hearings on the US-Soviet treaty banning medium-range missiles. The Reagan administration and Senate arms control proponents have clearly been put on the defensive by the arguments of Sen. Jesse Helms (R) of North Carolina and other conservative opponents of the pact.

Senator Helms's complaint that the treaty would not literally destroy warheads received so much attention that Secretary of Defense Frank Carlucci, on Monday, felt compelled to bring missile models before the Foreign Relations Committee to demonstrate what would and wouldn't be scrapped.

The intermediate-range nuclear forces (INF) treaty itself still seems headed for relatively easy Senate ratification. Critics appear to be using the INF hearings as a soapbox from which to influence crucial national defense decisions that will be made after treaty ratification.

In particular, they seem to be aiming at the current strategic arms reduction talks (START) in Geneva on 50 percent cuts in long-range nuclear arsenals. ``The right wing ought to be trying to kill START through INF,'' says a congressional aide who follows arms control.

Conservatives deny they are trying to stop strategic talks outright. Among positions that INF pact critics have taken:

There should be no reductions in strategic weapons without agreement to reduce conventional arms in Europe. In making this point Monday, retired Gen. Bernard Rogers, former military chief of NATO, complained that the United States ``should have at least tried'' to link conventional reductions with the INF treaty.

A strategic weapons treaty should have even stricter verification provisions than the INF pact. Defense Secretary Carlucci has agreed with this point, saying that any START treaty would have to include a provision allowing US inspectors to visit any suspect Soviet missile site they want to.

The US ought to be prepared to withdraw from the INF pact if the Soviets cheat. ``Some kind of language to that effect'' ought to be in the treaty, General Rogers said.

Rogers has long said bluntly that the INF treaty gives him ``gas pains.'' His successor as NATO commander, Army Gen. John Galvin, said the treaty will not undercut the alliance's ability to maintain peace in Europe.

``The treaty, if ratified, will still allow me to carry out my mission, which is to maintain deterrence,'' General Galvin told the Senate Armed Services Committee yesterday. Galvin said NATO needs to improve its conventional forces but said they present ``a real deterrent to the Warsaw Pact.''

Rogers's criticism of the treaty was praised by conservatives such as Sen. Dan Quayle (R) of Indiana and Sen. Steve Symms (R) of Idaho.

Helms, however, has clearly led the treaty opposition. From his seat on the Foreign Relations Committee he has gleefully badgered administration witnesses.

One of his primary charges has been that the Soviets are already violating the pact by concealing between 165 and 300 SS-20 missiles. This charge is based on a past estimate of the SS-20 arsenal produced by the Defense Intelligence Agency.

Administration officials countered that the Central Intelligence Agency had a lower estimate of SS-20 numbers, and therefore believes that the number the Soviets say they possess is accurate.

Carlucci said that in any case, the USSR would not be able to test missiles from such a hidden cache, and thus they would quickly lose any military effectiveness.

Helms also garnered much publicity for complaining that the treaty does not require destruction of actual warheads. Thus nuclear explosives could be removed from SS-20s and simply rebolted onto new weapons aimed at the US, he charged.

Administration officials admit that the INF pact does not literally require warhead destruction. Though launchers, missile boosters, and nose cone shrouds would be shredded, important interior portions - radars, warhead packages containing fissile material, and guidance systems - can be kept intact.

First of all, Carlucci said, destruction of fissile material is a ``virtual impossibility.'' Second of all, he said, it is in the US interest to keep these interior portions around, as it is much easier for the Soviet Union to produce crucial uranium and other radioactive elements.

Finally, it is not true that SS-20 components can simply be screwed on to other missiles, Carlucci said. ``This could not be done without some redesign and some testing,'' the defense secretary said.