MOSCOW, DEC. 16 -- A subtle rumbling of dissent has broken a general mood of jubilation here over the U.S.-Soviet agreement to scrap medium- and shorter-range missiles that was signed at the summit in Washington last week.

One Soviet war veteran griped about the treaty even before it was signed, using the newspaper Pravda to warn Kremlin leaders against being swindled by the Reagan administration.

"Is it really possible to trust the U.S. leadership?" M. Linyak asked rhetorically in the official Communist Party publication. "American imperialism hasn't given up its quest for military superiority."

Since Soviet leader Mikhail Gorbachev sealed the Intermediate-range Nuclear Forces (INF) accord in Washington, other complaints about it and the Kremlin leadership's general advocacy of disarmament have surfaced in scattered articles in the official media.

Although it has been dismissed by senior party officials, the grumbling indicates that the Kremlin's disarmament policy is probably disputed, some western diplomats said, if only by a minority of rank-and-file party members and military officials.

Nevertheless, in a show of glasnost, or openness, these skeptics appear to be getting a public airing.

No sooner was the treaty signed than a writer in the military newspaper Krasnaya Zvesda (Red Star) cautioned against a mood of pacifism creeping across the Soviet Union. Others charged Moscow with making a raw deal, since the treaty calls for the Soviet Union to destroy twice as many missiles as the United States.

In apparent response to the skeptics, Gorbachev, Army Chief of Staff Sergei Akhromeyev and other leading officials who took part in INF negotiations have been defensive in their public explanations of the treaty terms.

Akhromeyev, conceding in Pravda today that the Soviet Union is required to destroy more missiles, said, "It was important to deal not only with the arithmetic correlation of forces, but also with who should take the first step toward the beginning of disarmament.

"A positive outcome to negotiations is only possible on a reciprocal basis when both sides make concessions," the 64-year-old official said. "That is how it was in preparing the treaty on medium- and short{er}-range missiles. At the same time, the defense capacity of our country is ensured."

Akhromeyev, at pains to show that the Soviet military's interests were protected during the talks in Washington, said that Soviet negotiators had resisted a U.S. attempt to win a more lenient approach to Reagan's Strategic Defense Initiative, or "Star Wars," program.

"The American experts were proposing to us that they would be creating an {antiballistic missile} system for their country," he said. "We came out decisively against that.

"In order to prevent this, we managed to have recorded in the final joint statement that both sides were obliged to observe the ABM treaty in the form in which it was signed in 1972," he said.

In another signal of discontent, an official Soviet spokesman opened the first Moscow briefing after the summit with a striking defense of the Washington treaty, under which both the United States and the Soviet Union will be required to eliminate all of their medium- and shorter-range missiles.

"It is not an easy thing to give up nuclear missiles," Foreign Ministry spokesman Boris Pyadyshev said yesterday. "Some people believe that they are a symbol of a country's might, of its power over circumstances. Some people maintain that by giving up nuclear missiles a country loses the accessories of a great power. This is an entirely wrong assumption."

In a Monday night appearance on Soviet television, Gorbachev, too, seemed at pains to stress that the treaty was carefully weighed so as not to leave the Soviet Union at a military disadvantage.

Gorbachev also said that in preparing for the summit, the ruling Politburo's members discussed several times "the principled stand from which we would act there, and were once again calculating everything from the military-technical viewpoint."

Gorbachev, who hinted in talks with U.S. congressmen that the INF treaty might face a debate before ratification by the Soviet legislature, reiterated the point in his speech Monday. Referring to the Supreme Soviet, he said, "I hope that it will back the agreement, for such is the will of our people."

The nominal legislature is composed solely of Communist Party members and has not in memory rejected a bill put forward by the party.

During his 20-minute televised speech, Gorbachev struck western viewers and some Soviets as defensive about the treaty and his campaign for nuclear disarmament.

By stressing that the Politburo had collaborated in summit preparations and that the Soviet allies had approved the results, "he seemed eager to emphasize that going for the treaty was a group decision and not his alone," a senior western diplomat said. "He appeared to be arguing with doubts about the whole thing expressed by a skeptical, off-camera interlocuter."

In a show of glasnost, some of the skeptics now appear to be moving on-camera. In an official Soviet poll of attitudes toward disarmament and the treaty, released this week in the official magazine New Times, 20 percent of those questioned said that Moscow should seek military superiority rather than parity.

According to an article last Thursday in the official newspaper Sovietskaya Rossiya, factory workers in Votkinsk, who would have to transfer from defense to civilian industry as a result of the treaty, noted that the switch would result in some "shortages."