BONN, JULY 26 -- The Soviet Union has relaxed its policy toward the two Germanys in recent months, a major diplomatic shift that could help ease tensions on the front line of East-West confrontation, western officials and analysts say.

In the most dramatic manifestation of the new policy, Soviet leader Mikhail Gorbachev has given his blessing to an unprecedented trip by East German chief of state Erich Honecker to West Germany in September. The Soviets vetoed such a trip in 1983 and 1984, but according to West German officials and western diplomats, Gorbachev told Honecker at a Warsaw Pact summit in East Berlin at the end of May that Moscow now had no objection.

The visit, if successful, could lead to an inter-German thaw that is deeply desired in both halves of the divided nation.

The East Germans are pressing Bonn to ante up money for railway, highway and energy projects in East Germany, while the West Germans want Honecker to accelerate recent modest moves to lower travel barriers between the two states and to ease other human rights restrictions.

In addition, the Soviets now appear determined to resume cordial relations with West Germany after a four-year diplomatic chill that resulted from Bonn's 1983 decision to deploy U.S. medium-range missiles.

West German President Richard von Weizsaecker made a generally successful state visit to Moscow earlier this month -- the first such trip in 15 years.

Soviet Foreign Minister Eduard Shevardnadze is scheduled to make a long-delayed trip to Bonn in the fall, and officials here predict that Gorbachev will come here next year for the first time.

Moscow is "resolved to improve bilateral relations and to come to stable relations without any ups and downs," a high-ranking West German official said, adding, "This is a result of the von Weizsaecker visit."

The Soviets' new German policy apparently has multiple aims, according to official and private analysts.

First, Gorbachev would like to increase economic cooperation with West Germany to obtain western technology and credits to help his modernization program.

West Germany is the Soviet Union's largest trading partner in the West, and the Soviets told von Weizsaecker that strengthening of economic ties is a top priority for them.

In addition, the Soviets want to encourage West Germany to take a more neutral foreign policy stance. They would like to capitalize on public enthusiasm here for Gorbachev's reform program and for his concessions in arms control negotiations with the United States.

"It seems to me that the Soviets have decided to experiment a little more in Germany," a senior western diplomat said. "They want to test the Germans and see if they're available."

At present, the most serious issue dividing Bonn and Moscow concerns West Germany's desire to retain 72 antiquated, short-range Pershing IA missiles and their U.S.-controlled warheads despite an expected U.S.-Soviet treaty to scrap similar weapons worldwide.

The Soviets have identified the issue as a major obstacle to a treaty, and analysts said that Bonn would be under pressure to modify its stance to avoid letting it sour the climate for the Honecker trip scheduled for Sept. 7-11.

Moscow also wants to press Bonn to be more assertive in expressing its reservations about the U.S. space-based defense program known as the Strategic Defense Initiative.

The Soviets want to reward West German Foreign Minister Hans-Dietrich Genscher for his high-profile policy of urging the West to encourage Gorbachev's reform program. Finally, the Soviets hope that a more relaxed policy on inter-German relations will help keep Honecker happy.

Among the Soviets' Eastern European allies, the East Germans are known to be the most critical of Gorbachev's program of glasnost, or openness, and other political reforms. East Germany also has the Eastern Bloc's strongest economy.

"I think the Soviets can best assure Honecker's allegiance to them by including him in their western policy," Theo Sommer, a foreign affairs specialist and editor of the weekly newspaper Die Zeit, said. "He has a lot of standing, and he has a lot of economic clout."

Some observers here said that the current trends in German-Soviet and inter-German relations, if they continue, could lay the basis for what Genscher has called a "second phase of realistic detente."

These analysts noted that a key component of detente's "first phase" in the early 1970s was the improvement in Bonn's relations with the Eastern Bloc engineered by then-chancellor Willy Brandt.

Both Honecker and West German Chancellor Helmut Kohl stand to reap political gains from improved inter-German relations.

For Honecker, the trip to West Germany would mark Bonn's strongest endorsement yet of the legitimacy of East Germany. Bonn officially does not view East Germany as a sovereign country, but rather as a separate state that is part of one German nation. Bonn maintains diplomatic relations with East Berlin at a less-than-ambassadorial level, and refuses to recognize the inter-German border as a permanent one.

For Kohl, an improvement in relations with the East would be a valuable political weapon in fending off criticism from the leftist opposition that his center-right government is a barrier to peace.

Nevertheless, there are important political and economic limits to a new process of detente. The Soviets are so preoccupied with domestic economic issues that they have not identified specific projects by which the West Germans or other western countries could help.

Moreover, Kohl's government is dominated by conservatives, many of whom are skeptical of better relations with communist governments.

The East German government, for its part, has sent mixed signals about its willingness to improve its human rights policies.

Since February 1986 East Berlin has allowed a dramatic increase since February, 1986 in the number of persons below retirement age granted permission to make short visits to West Germany. But the government recently reduced from $38 to $8 the amount of money a citizen may convert to West German marks to make the trip.

Finally, the Soviets are likely to keep the East Germans from going too far in warming relations with Bonn. Both the Soviets and their other Eastern European allies, particularly the Poles, get nervous when the two Germanys move closer to each other. They remember a united Germany under Adolf Hitler.

"When there is some destabilization at home in the Soviet Union due to the reforms, they would not dare create a destabilization in the center of Europe," said Guenter Gaus, an author and Bonn's former chief representative in East Berlin.