US reports slight progress toward a chemical-arms pact. Soviets agree on some of chemicals affected, hint at regular inspections

In recent months, the United States and the Soviet Union have made modest progress toward a treaty that would ban all chemical weapons. Meanwhile, the Pentagon is preparing to resume making chemical bombs and shells. One legal hurdle remains to be cleared if production is to begin on schedule.

During the latest round of chemical-arms control talks in Geneva, which ended three weeks ago, Soviet negotiators ``came forward a little bit in a couple of areas,'' says a senior administration arms control official.

One of these areas was commercial chemicals. US and Soviet negotiators reached tentative agreement on a list of some commercially available chemicals that can also be used in weapons production, and so should be part of any weapons ban. On the list are phosgene (used in World War I) and hydrogen cyanide, among others.

Small gains were also made on the issue of dismantling chemical-weapons plants. Just as the round of talks was concluding, the Soviets made a new proposal on how such destruction could be verified. The Soviets hinted that they might accept routine, scheduled inspection of factory areas to make sure no chemical-weapons production was taking place. Previously, Soviet negotiators had insisted that inspections should be purely voluntary.

But the Reagan administration has insisted that inspections should be ``on challenge'' -- whenever the inspecting party wants. Thus, the superpowers are still on opposite sides of a tall fence as far as verification is concerned. There is very little likelihood of quick agreement when talks resume in June.

``The crux of the problem is still verification,'' says the senior Reagan administration official.

The latest effort on chemical-arms control dates back to 1980, when the Reagan administration proposed a draft treaty. Talks have proceeded in the forum of the United Nations Committee on Disarmament, a body with 40 member nations that meets in Geneva. The chemical talks received a shove last fall when, at their summit conference, President Reagan and Soviet leader Mikhail Gorbachev pledged to accelerate work on the issue.

In January, as part of his sweeping arms-limitation initiative, Mr. Gorbachev proposed an interim agreement banning deployment of chemical weapons. The Reagan administration rejected this proposal, arguing that the USSR could ship chemical weapons to a European front far more quickly than could the US.

Against this background, the administration is close to resuming US chemical-arms production. Pentagon officials have argued for years that as long as there is no formal ban on the weapons, the US should modernize its aging stockpile of chemical bombs and artillery shells. Congress finally bought the argument last year and set aside money in the fiscal 1986 budget for new shells and bombs. Production can begin no earlier than this Oct. 1.

But lawmakers included a catch: Before the money could be spent, NATO allies had to formally approve ``force goals'' outlining the need for the weapons.

Chemical weapons are very unpopular among West Europeans generally. A number of allied governments wish the issue would go away without their having to take a stand. That won't happen. The Reagan administration plans to ask a late-May meeting of NATO defense ministers to approve its chemical-arms plan.

The outcome is uncertain, and critics in Congress argue that even if the defense ministers go along, it's not good enough. The defense appropriations bill states that the chemical-weapons plan must be approved by the North Atlantic Council, NATO's highest decisionmaking body. Critics say the administration is going to the defense ministers because it feels they will be more amenable to its plans than would the full council, which is usually made up of foreign ministers.