While sentiment for increased defense spending grows in Washington, officials in Eastern Europe are worried that their own military budgets will have to be increased on orders from Moscow if relations between the United States and the Soviet Union take a turn for the worse.

Specifically, officials here and in Poland -- two countries with relatively good relations with Washington -- are worried about what will happen to superior relations if the strategic arms limitations treaty (SALT II) is not ratified in the U.S. Senate or if NATO, as expected, goes ahead with its plan to modernize its nuclear forces in Western Europe with new U.S.-built medium-range missiles.

The East European arguments fit into what has become a massive Soviet propaganda campaign aimed at the West and designed to keep the West European allies from actually deploying these new American weapons on their soil.

There is, however, a large dose of reality in these arguments for East Europeans, all of whom are under serious economic pressures of their own and who fear that a demand for higher military spending will make matters worse.

"We are still quite poor, have a lot of economic problems and have difficulties with our trade balance," said one senior official who asked not to be identified. "So if there is a chance not to buy new weapons and get security at a lower level of armaments, that would be very helpful.

"It is not so simple, indeed it is not true," he continued, "that the Soviets will automatically press what Westerners call their 'puppet governments' to cut back on their dealings with the U.S." if things turn sour.

"But for sure, if there is a new cold war, there will be more money for defense. The terms of trade will be much harder. There will be less money for other things, fewer products to sell. . . Things will be tougher and it will affect our everyday life," he added.

If SALT II is not ratified, "it would be a very serious blow to detente and people in this part of the world would ask a very serious question about what the U.S. is up to," another official said.

During recent interviews in the Polish Foreign Ministry in Warsaw, officials gave similar answers, adding that failure to ratify "would be such a disappointment that it would be hard to predict what would happen. The conclusion, however, would probably be that it is hard to negotiate with the U.S. . . . The reaction would probably be that the only practical answer would be an arms race."

When asked how this would be explained to the Polich people, he said, "When you speak with Poles about war, it is not the U.S. Army but the German Army that people think of. And even though the economic situation here is not good, when you talk of war and the German Army, and if a specific purpose is clearly seen by the population, they will make the sacrifice."

The Warsaw Pact governments do not have to explaine their actions to balky parliaments, as in the West. Yet it is not true that they can always act independently of their populations. Bread-and-butter economic issues in Eastern Europe have caused several worker uprisings in the post war years, so that the matter is indeed touchy.

Officials in both countries expected the SALT II would be approved in the final showdown and if that happens the longer running problem will be the NATO modernization plan.

The NATO plan involves eventually deploying, beginning in late 1983, about 572 U.S.-produced Pershing II missiles and Tomahawk cruise missiles in Western Europe as a counter to more than 100 new multiple-warhead Soviet SS20 missiles already in place plus scores of new Backfire bombers. Both weapons are targeted primarily on Western Europe.

The East Europeans argue, however, that by installing new U.S. missiles in Western Europe with enough range, for the first time, to hit targets in the Soviet Union, the West is actually adding to the weapons that can strike the Soviet heartleand in a war. Since these weapons are not covered by the ceilings on strategic weapons covered by the SALT pact, the East argues that the West is using these new arms to circumvent the SALT limitations. The Soviets, in turn, are adding weapons to their arsenal.

This argument can, and has been, challenged by the West on several grounds. But it has a certain force and logic here, in terms of explaining the situation to the public.

Officials in both countries indicate that the Kremlin is resigned to the fact that NATO will go ahead with its plan to put the new U.S. missiles into production and development.

The officials also suggest, however, that it might be a long and uncertain time before Moscow agrees to negotiate. "I do not believe that a proposal made right after a decision on deploying new nuclear missiles in Europe will be gladly accepted on the same day," one senior official here says.