The Soviet Union appears to be mounting a new "peace offensive" not only to burnish its image in the West but to reassure its allies that Moscow's arms control policy is not being paralyzed by the long illness of President Konstantin Chernenko and the prospect of another leadership change in the Kremlin.

Less than three weeks before the United States and the Soviet Union resume nuclear arms talks in Geneva, NATO representatives said they have been struck by the flurry of Soviet-sponsored initiatives in other East-West negotiations.

"It seems that Moscow wants to make a show of activity this time to prove that its long-term arms strategy is not affected by Chernenko's illness," a senior western diplomat said. "Last year, when he appeared gravely sick, the Soviets were locked in their freeze on contacts with the West."

Moscow's decision to drop its demand that Pershing II and cruise missiles must be removed from Europe before returning to nuclear arms talks reflected its recognition of the widespread unease in Soviet Bloc capitals with the suspension of dialogue with the West as well as its failure to intimidate Western Europe, NATO officials said.

Since agreeing in January to return to Geneva, the Soviet Union has embarked on a dual campaign to exploit differences between the United States and its European allies over fears about an arms race in space and to assume a more active profile with its allies in disarmament forums.

Soviet officials repeatedly have warned that any chances for early agreement curtailing arsenals of medium-range weapons in Europe or intercontinental nuclear missiles will be nullified if the United States pursues plans for space-based defensive systems.

But Moscow also has taken pains to exhibit a readiness to participate again in arms control negotiations by "repackaging" old proposals and flourishing them before the 35-nation European Disarmament Conference in Stockholm and the East-West troop reduction talks here.

"Moscow's East European allies are much more comfortable with the so-called cooperative Soviet posture, even if the proposals are not really new," a NATO ambassador here said. "The East Europeans like these forums and Moscow now seems to be obliging them."

Two weeks ago, the Soviet Union, Bulgaria and East Germany submitted a plan calling for military exercises by NATO and Warsaw Pact armies to be restricted to no more than 40,000 troops as a way to reduce the risk of war in Europe.

Delegates from NATO countries dismissed the Stockholm offer as unacceptable to the West because NATO exercises frequently involve more than 100,000 troops. They perceived the proposal largely as a public relations ploy to push NATO into the embarrassing position of rejecting a tangible offer.

Nonetheless, the Soviet Bloc countries argued that such large-scale exercises resembled the early stages of an attack and thus posed serious risks of provoking inadvertent warfare.

For its part, NATO is seeking regular exchanges of information on the nature, location and purpose of military activities as the most practical method to curtail risks of accidental conflict.

Last week, the Warsaw Pact unveiled a new offer designed to break the stalemate at the 11-year-old Vienna troop reduction talks. It called for the initial withdrawal of 20,000 Soviet troops and 13,000 U.S. soldiers from Central Europe within one year, to be followed by the reduction of Warsaw Pact and NATO ground forces to no more than 700,000 on each side.

In addition, as a good will gesture, the Warsaw Pact proposal would have all states in the Central European theater -- West Germany, Belgium, the Netherlands and Luxembourg in the West and East Germany, Poland and Czechoslovakia in the East -- freeze the number of their soldiers for three years.

NATO countries have proposed that the Soviet Union initially pull out 30,000 troops instead of 20,000. But the real obstacle to progress in the Vienna negotiations over the years has been intractable disagreement over the number of troops deployed by both sides. NATO believes that Warsaw Pact forces underestimate their strength by more than 150,000 men.

To surmount the dispute over figures, NATO offered last April to concentrate only on combat forces and forego the difficult task of assessing support troops.

"It's still hard to say whether Moscow is interested in resolving the deadlock in the Vienna talks, or just engaging in tactical games to put us on the defensive," a senior NATO representative here said. "We are being careful not to knock down or embrace their latest offer."