Thirty-five years after the end of World War II, the Germans have placed themselves squarely among the world's political heavyweights again.

In a bold statement last week, Chancellor Helmut Schmidt proclaimed a "leading role" for West Germany in world affairs. He also said Bonn had grown out of its "client" relationship with Washington into a position as a "real partner" to the United States.

Coming in the middle of a year of squabbling among the allies over East-West relations, Middle East peace policy and Western trade practices, Schmidt's remarks in a Cologne newspaper interview underlined the qualitative change in the West German view of the relationship between America and its European allies.

As much as anything, Schmidt's own forceful image and his calculated efforts to project an air of authority have dramatized Bonn's more assertive stance.

Recently, the West German chancellor publicly criticized President Carter for sending a letter that called into question Schmidt's position on Western defense policy. Futhermore, for some time now, Schmidt's private, off-the-cuff remarks about Carter's "unpredictable" foreign policy have become public, gaining widespread European assent while remaining a periodic source of White House irritation.

Now, two months before Schmidt faces a federal election, his strong words about Bonn's enlarged world role and independence from Washington seem timed mainly for his reelection campaign. Although pitched to a home audience, Schmidt's statement is according to chancellery aides, his clearest yet on West Germany as an "economic giant but political dwarf."

Although it has been evident for some time that the Germans have shaken off much of the postwar reticence about their regained stature, Schmidt's comments mark a formal turning point.

Underpinning West Germany's greater political stature is its economic power. As Schmidt proudly stated, his country is today second only to the United States in economic influence, controlling the largest currency reserves and second-largest gold reserves in the world.

The dilemma for Bonn has been how and when to convert this economic strength into political capital without angering Washington, antagonizing Moscow and upsetting European neighbors who still get nervous whenever the Germans appear too strong. At the core of this shift is the changing nature of the U.S.-West German relationship, balanced against the development of cooperative Soviet-West German ties.

"We are no longer compelled uncritically to adopt any U.S. position," Schmidt told the Cologne Stadt-Anzeiger. "The U.S.-German relationship today is different from what it was 15, 20 or 25 years ago. Then we were a dependent client; today we are a major partner of the United States."

Not wanting to speak of "conflicts" with the United States, Schmidt said there are nonetheless "different interests" between West Germany and America.

While saying that America is still West Germany's most important ally, the chancellor stressed that Bonn and Washington "will have to get used to the fact that they are real and not only nominal partners."

Schmidt called recent reports of anti-Americanism in West Germany "destructive nonsense." Even so, he seemed to play on such sentiment.

In a comment, the respected Frankfurter Allgemeine newspaper cautioned against overstressing Bonn's independence from Washington. Noting that distrust toward West Germany is "in the air" in the United States, the paper wrote, "Even Washington's assurance that it has every understanding for us does not relieve us of the need to take account of this basic current in the American nation. Not all changes in our relations with the United States are exclusively in our favor."

Sensitive to the historical and political constraints that still restrict West German foreign policy, Schmidt carefully seeded his declaration of Bonn's new leadership role with qualifiers.

West Germany, he said, is not a world power and does not want to become one, preferring to remain a "middle" power. France and Britain, he said, still have more freedom of action in foreign policy than West Germany. This is partly due to handicaps imposed on Bonn from outside, including the division of Germany and the partition of Berlin. It is also due to Bonn's self-imposed lack of nuclear weapons.

"We are not nor do we want to become, a nuclear power," Schmidt said. He also ruled out West German assistance for a European nuclear force independent of the United States.

While deferring to the Washington-London-Paris lead on military nuclear policy, the chancellor nevertheless highlighted the key role his government played in last December's NATO decision to station medium-range nuclear missiles in Europe.

In general, Bonn has tried to incorporate its own foreign policy into common positions supported by the eight other member nations of the European Economic Community. Bonn sometimes has appeared to use the community to cloak its own designs, as through the creation a year ago of the European Monetary System.

Yet West Germany's own political rise has been apparent for some time. It was formally recognized in January 1979 at the Guadeloupe summit, when for the first time the Big Three was enlarged to include the Germans. On that occasion Bonn was charged with a special mission to organize aid for Turkey.

In recent months the West Germans seem to have been increasingly active. Following the Soviet invasion of Afghanistan in December, Bonn took responsibility for NATO efforts to shore up the Turkish-Greek southeastern flank. In the Middle East, West German finance and economic ministers have pursued rich deals with Arab states, while the Bonn Foreign Ministry tilted with other European governments away from Israel and Washington on the question of Palestinian autonomy.

Earlier this year, Defense Minister Hans Apel paid an unprecedented visit to Asia. In Latin America, the governing Social Democratic Party is promoting leftist factions, sometimes at Washington's annoyance.

Moreover, despite the cooling in U.S.-Soviet relations, West Germany has appeared determined to conduct business as usual with Moscow. German businesses are pursuing large trade deals with the Soviets, and Bonn continues to promote cooperative relations with the Kremlin.

[Soviet President Leonid Brezhnev and Premier Alexei Kosygin have called West Germany's efforts toward East-West detente "the decisive factor for stability in Europe," news services quoted Tass as reporting Monday.]

[The Soviet news agency said the Kremlin leaders made the observation in a message to West German President Karl Carstens and Chancellor Schmidt marking the 10th anniversary of the Soviet-German treaty that spurred Bonn's detente -- oriented ospolitic or eastern policy. The policy launched an era of expanding West German trade and diplomacy with Eastern Europe and provided Bonn with a flexibility in foreign policy it previously had been denied.]

While West German athletes stayed away from the Moscow Olympics, Schmidt traveled to Moscow at the end of June for talks with Brezhnev. In fact, Schmidt took credit last week for getting Washington and Moscow talking to each other again.

He said his Moscow visit -- together with French President Valery Giscard d'Estaing's darting trip to Warsaw in May, also to see Brezhnev -- "contributed to preventing a mistake that both world powers were about to make in their relationship to one another."

Schmidt's remarks were keyed to the 10th anniversary this week of the Bonn-Moscow treaty.