If a country needs enemies to retain its identity, the United States could be in big trouble.

Ten years have passed since the United States officially recognized China, making this an appropriate time to dwell on a contemporary phenomenon: Americans have fewer people to loathe these days.China has been transformed from the totalitarian, expansionist "yellow peril" into a gang of capitalist roaders, a billion strong, who see nothing wrong with making a buck and cutting deals with Washington.

Even more remarkable is the transformation in relations with the Soviet Union. Five years ago, President Reagan was engaging in his "evil empire" rhetoric about the Soviets, and Americans were pouring Russian vodka down the drain to protest the shooting down of a Korean Air Lines passenger plane by a Soviet missile.

Nowadays, President Mikhail Gorbachev gets uniformly high marks in U.S. public opinion polls and Americans are sending relief packages to earthquake victims in Soviet Armenia. U.S. government and private donations as of Monday totaled $3.2 million.

State Department spokesman Charles Redman said Monday the response merely reflects the magnitude of the disaster in Armenia but it seems improbable that a comparable level of generosity would have been in evidence if the tragedy had occurred in that vintage Cold War year, 1983.

"Who today are the men we love to hate?" asked Charles Paul Freund of the Washington Post.

He recalled that Georgi Arbatov, Moscow's leading U.S. expert, once said facetiously that the Soviet show of friendship was really an anti-American plot.

"We'll deprive America of its enemy," Arbatov reportedly said, forcing the United States to focus on internal problems. Heretofore, American attention had been diverted by the need to contain the communist menace.

"I don't know what we will do," former CIA official Graham Fuller said last week, "without the Soviet Union as a touchstone for Third World policy."

The Soviet Union and China are not the only nations that have disappeared from the American pantheon of evildoers. Latin America, for example, is running low on military dictators, long a favorite target of Democrats.

In Africa, Uganda's Idi Amin has been reduced to irrelevant exile. Libya's Moammar Gadhafi doesn't seem to arouse as much indignation as he did before the U.S. Air Force bombed him.

Remember OPEC? Hatred for that group disappeared with the gas lines.

To be sure, there are people abroad against whom Americans can rally. Ayatollah Ruhollah Khomeini still rules Iran under a "death to America" banner. And his friends in Lebanon who continue to hold Americans hostage are viewed almost universally by Americans as perhaps the world's least congenial people.

Finally, there is Fidel Castro, who in two weeks will celebrate 30 years of non-stop anti-Americanism.