The Soviet Union today faces governments in the United States, Western Europe and Japan that are more deeply suspicious of Kremlin motives than at any time in the past decade and generally are more prepared to back up that view by countering Soviet moves in such sensitive arenas as nuclear weaponry and counterintelligence.

The full impact of this change in the tenor of official ties is only beginning to be felt, but already East-West political relations have plunged to their lowest point in years.

"There undoubtedly has been a major shift against Moscow's interests," said a senior western diplomat. "What we don't know yet is where it will lead."

The victory of Chancellor Helmut Kohl's conservative-led coalition in West Germany last month, the steep decline in the longstanding French-Soviet special relationship symbolized by Socialist President Francois Mitterrand's expulsion of 47 alleged Soviet spies and the emergence of a Japanese prime minister intent on increased defense spending are the latest developments in a process that began with the elections of two avowedly anti-Soviet leaders, President Reagan and Britain's Prime Minister Margaret Thatcher.

In Moscow, Georgy Arbatov, the senior Kremlin adviser on U.S. affairs, said in an interview that U.S.-Soviet relations "have entered a very dangerous period." Details on Page A28.

Thus far, the extent to which Moscow is coping with increasingly hard-nosed governments in the West and Japan has competed for attention with the alliance's own problems. The public debate about U.S. nuclear missiles based in Western Europe and the continuing serious differences on the scope of trade with the Soviets have created an impression more of disarray than unity in challenging the Kremlin. Widespread concern over what is seen by some as Reagan's shrillness has not disappeared nor has the feeling among some U.S. officials that the Europeans are still not carrying their full weight on defense.

Particularly on trade matters, the Europeans, all of whom have serious economic problems, are resisting American efforts to apply stringent new restrictions on exports to the Soviets. The Kohl government also has a strong need to preserve as much access as possible to East Germany for its citizens, and that seems to depend on maintaining civil relations with the Soviets.

In the 1960s and 1970s, key western governments made improved relations with the Soviets a cornerstone of their foreign policies. On the whole, the Soviets reciprocated, and the political climate improved.

What has changed dramatically in recent years is that the previous western governments are gone. In their place are administrations that share a greater concern about growing Soviet military strength and are less ready to rationalize Kremlin wrongdoing than their predecessors. Substantial public opposition to deployment of new medium-range nuclear missiles in Europe has been overridden by the leaders, although they do remain eager for U.S.-Soviet negotiations on the issue to succeed.

"We aren't as worried about neutralist sentiment in Europe as we were," said a Reagan administration official on a visit here. "You can always get a big crowd to demonstrate against nuclear weapons, but the governments themselves are ready to take a harder line toward the Soviets. In the end, that's what counts."

In West Germany, the Social Democratic Party of former chancellors Willy Brandt and Helmut Schmidt, who fostered the opening to the East Bloc known as Ostpolitik, is out of power, decisively beaten at the polls. During the recent West German election campaign, the Soviets went to such lengths in pressing for a return of the Social Democrats that Kohl's government lashed out at the Kremlin's "massive interference" in West German internal affairs.

In France, the detente policy inaugurated by Charles de Gaulle in the 1960s and pursued by his successors Georges Pompidou and Valery Giscard d'Estaing has been superseded by Mitterrand's support of a strong "Atlanticist" position on the missiles question and, as of this week, a firm stance against espionage.

"President Mitterrand has repeatedly made it clear that he is one of the firmest anticommunists in Western Europe," the British weekly The Economist observed, "and the French president knows Communists better than Reagan--he still has two of them in his Cabinet."

Later this year a NATO Council meeting of foreign ministers will take place in Paris for the first time since de Gaulle took France out of the alliance's military structure in 1966. Mitterrand has been notably outspoken about what he calls "the intolerable threat" posed by the buildup of Soviet SS20 missiles and France's commitment to maintain its own nuclear deterrent. In January, he told the West German Bundestag that the "common determination of the members of the Atlantic alliance must be clearly confirmed."

Further proof that suspicion of the Soviets exists in left-wing governments as well as conservative ones is that Mitterrand's new Socialist neighbor in Spain, Premier Felipe Gonzalez, also has expressed support for NATO's missile plan.

The Labor governments of the 1960s and 1970s in Britain never got as far as France or West Germany in cultivating the Soviets. But their view was, nonetheless, vastly different from that of Margaret Thatcher's Conservatives today. In the face of Moscow's "huge levels of military expenditure and their record in Eastern Europe and Afghanistan," Foreign Secretary Francis Pym said in a speech late last year, the alliance can no longer afford "to put our trust in the Russians' good intentions."

On the other side of the globe, Japanese Prime Minister Yasuhiro Nakasone's commitment to a bigger defense budget and his controversial assertion that Japan should be like "an unsinkable aircraft carrier" represent a significant break with that country's postwar strategy.

Reagan is the most vociferously anti-Soviet leader of all, especially when contrasted with the policies favoring detente of so staunch a conservative as Richard Nixon. The difference between Reagan's view that the Soviet Union is an "evil empire" and Nixon's pledge when he was president to make "detente irreversible" reflects how much worse the atmosphere is now compared to a decade ago.

As for the drive to curb Soviet espionage, the expulsion of alleged Soviet spies from France this week was the most spectacular recent event of its kind. But Soviets also have been ousted this year from Britain, West Germany and Italy. Moreover, Italian officials have been pressing their potentially explosive investigation of a "Bulgarian connection" to the attempted assassination of Pope John Paul II in May 1981.

In the 1970s, U.S. officials were worried about the rise of Eurocommunism, fearing that although the Communist Parties of France, Spain and Italy were nominally independent of the Kremlin, they shared many of its objectives in foreign and domestic policies. But today, the French party, which had been the most closely aligned to the Soviets, supports Mitterrand's position on the nuclear issue.

The Italian Communists never made it into the national government and, in any case, they are further estranged from Soviet ideology than ever. The Spanish party has lost significance as Gonzalez's Socialists have expanded their influence.