Next on arms talks. A pact eliminating shorter-range nuclear missiles, which appears certain now, is seen as significant primarily for the momentum it could impart to talks on strategic weapons. And it will boost Gorbachev at home. Stories below, Page 9.

Is there life after INF? Now that Moscow and Washington are wrapping up an agreement to ban all intermediate-range nuclear forces - INF - the question is whether the superpowers can resolve the major stumbling block to a broader accord on strategic nuclear arms. The obstacle is President Reagan's ``star wars'' program and reinterpretation of the Anti-Ballistic Missile treaty.

Publicly, both sides are sending out positive signals.

White House officials say they are encouraged by the talks between Secretary of State George Shultz and Soviet Foreign Minister Eduard Shevardnadze, and also by Soviet leader Mikhail Gorbachev's recent statement suggesting that a START (strategic arms talks) agreement is possible in early 1988. Mr. Gorbachev mentioned the possibility not only of a fall summit this year but also of another summit meeting next year.

``I'm guardedly optimistic,'' says a high White House official of the prospects for a START pact. ``They are very tough bargainers, and I think it is never useful to give away your own bargaining position. But I think the very fact that the general secretary has made favorable remarks about the next and next after that summit in prospect is mildly encouraging.''

Administration officials also note that Gorbachev did not make any linkage between the President's Strategic Defense Initiative (SDI) program and START. This new flexibility was reflected in the Shultz-Shevardnadze talks this past week.

The Soviets say they realize they cannot persuade Reagan to abandon his plans for a space-based antimissile defense system and are therefore focusing on making a START agreement contingent on strict compliance with the ABM treaty. The difficulty is that the administration has adopted a broad interpretation of the treaty in order to pursue its SDI plans.

``We want you to stick to the ABM treaty for 10 years and we hope - though we don't say that - that in 10 years you will change your mind on SDI,'' said Soviet Foreign Ministry spokesman Gennady Gerasimov on Friday. In 10 years time, the Soviets calculate, they will be dealing with a different administration and SDI may have turned into a pipe dream.

The ABM treaty is the key to unlocking the START door, and it involves not only the President's views but those of Congress as well. The Soviets are carefully watching the activities of Sam Nunn (D) of Georgia, chairman of the Senate Armed Services Committee, who is determined to block the administration's attempted reinterpretation of the ABM treaty. The Senate recently voted to restrict any SDI testing outside the traditional or ``strict'' interpretation of the ABM pact.

The White House counts on vetoing the defense authorization bill containing these SDI curbs and on being able to sustain such a veto in the Senate. But it would then have to confront Senator Nunn's threat to reduce funding for SDI.

White House officials are concerned about the looming confrontation. ``This is the worst possible time to have a public dispute on the interpretation of the ABM treaty ...,'' says the high Reagan aide. ``It is a problem that won't go away and will have to be resolved, and I'm sure the President wishes to try to resolve it and if possible on a bipartisan basis.''

It remains to be seen how vigorously the President gets involved. But White House chief of staff Howard Baker Jr., a former Senate majority leader, says he is prepared to talk with former colleagues in the Senate ``to explore the possibility of depoliticizing this issue'' and achieving a bipartisan consensus.

Senator Nunn is also critical of the Soviets, however, for seeking an even more rigid interpretation of ABM than the traditional one, an interpretation which would bar what they call purposeful research.

``I don't agree with that position,'' he stated yesterday.

Soviet officials, meanwhile, having presented the United States with a detailed list of devices, including weapons prototypes, that could not be deployed under the ABM treaty, say the Reagan administration is handling the issue like a ``hot potato.'' Moscow is seeking a similar list from the American side. It also is calling for a meeting on ABM and other issues between Defense Secretary Caspar Weinberger and Soviet Defense Minister Dmitri Yazov in the Standing Consultative Commission, the US-Soviet group that deals with treaty compliance. The US has not not responded.

In the opinion of arms experts, the Soviets would be unwilling to start reducing their offensive strategic nuclear arms by 50 percent (as the two sides have agreed) without assurance that the US would not test and deploy defensive systems which they regard as threatening.

In Washington last week the two sides made headway on START as well as on INF. The Soviets agreed to limit the number of nuclear warheads on any one leg of the strategic triad - land-based missiles, submarines, or bombers - to 60 percent of the total arsenal. Progress was also made on the issue of sublimits, especially of heavy land-based missiles, which concern the Americans the most.

But the SDI/ABM issue has to be dealt with. The best hope of a breakthrough appears to lie in defining what is meant by ``components'' under the ABM treaty - that is, setting rules that give some scope for testing SDI research devices while banning weapons prototypes. Some US arms officials, including presidential arms adviser Paul Nitze, are prepared to be flexible, but the administration is still deeply divided on the issue.

President Reagan, for his part, shows no sign of compromise on SDI or ABM, and his close aides also appear to support the entrenched position. ``It seems to me extraordinarily difficult to agree to a list of permitted activities and prohibited activities when we don't know exactly what activities we're going to undertake,'' says the high White House official.

The INF treaty now agreed to ``in principle'' is deemed significant symbolically as a first step toward reducing the superpowers' nuclear arsenals. But it will encompass only short- and medium range weapons, which comprise only a small fraction of the nations' total nuclear armaments. Both sides, moreover, can quickly compensate for the reductions by retargeting their strategic or intercontinental missiles on Europe.

``Removal of the [US] Pershing 2 missiles in Europe is a good thing because they threaten Moscow's nuclear command system,'' says John Steinbruner, an arms expert at the Brookings Institution. ``So it benefits both sides to get rid of them.

``But elimination of the [Soviet] SS-20s does not diminish the threat to Europe since the SS-25 [the new Soviet mobile ICBM] will absorb those missions,'' Mr. Steinbruner adds. ``So the agreement is modest in its proportions.''