THE COLD WAR is won. But there are no celebrations in America, only much public fretting about the country's decline.
Some believe that the United States is overextended and should reduce its external commitments; no matter how justifiable, major military expeditions, such as that in the gulf, are beyond both its purse strings and its political power.
These beliefs are false. In a world of growing interdependence among nations, they are not just wrong, they are dangerous; indeed, it is a questionable premise whether the United States is in decline at all.
There is no doubt that the United States will be less powerful in 1991 than it was in 1950. The American share of world product has declined from more than one-third of the total in 1950 to 23 percent today.
That change, however, represents the artificial effect of the World War II. Unlike the other participants, the United States was strengthened by the war, but that preponderance was bound to erode as other nations regained their economic health.
Paul Kennedy, author of the best-selling "The Rise and Fall of the Great Powers," argues that the United States' share of world gross national product has declined much more quickly than it should have over the past few years.
Jacques Attali, first director of the new European Bank for Reconstruction and Development, argues that America has fallen to a "secondary position."
But the numbers do not support the argument. The American Council on Competitiveness has found that the country's share of world product has held constant at 23 percent since the mid-1970s. The Central Intelligence Agency, using numbers that reflect the purchasing power of different currencies, reports that it actually increased slightly in the 1980s.
What are the likely changes in world power in the l990s? The conventional guess is for a return to a balance among a number of nations with roughly equal power resources, analogous to the late 19th century.
But this is not likely to come about, for in terms of power resources, all the potential challengers except the United States are deficient in some respect. The Soviet Union and China lag both economically and in their political systems; Europe lacks political unity; Japan is deficient both in military power and in global ideological appeal.
If economic reforms reverse the Soviet Union's decline, if Japan develops a full-fledged nuclear and conventional military capability together with a leadership role in Asia, or if Europe dashes to a dramatic unification, there may be a return to the classical multipolarity of the late 19th century.
Barring such changes -- and none is immediately probable -- the United States will stay on top. It alone has the full range of power resources -- military, economic, scientific, cultural -- together with the will to use them.
The United States does have economic problems. Important industrial sectors such as consumer electronics and automobiles have slipped badly. The household savings rate dropped from 8 percent in the 1970s to 5 percent in the 1980s. In addition, government dissaving -- the fiscal deficit -- has caused another 3 percent drop in savings.
Since gross investment has stayed roughly the same, the missing savings have been made up by capital imports which have transformed the United States into the world's largest debtor nation in absolute terms.
There is, however, a positive side to the story. During the 1980s, the American economy grew by 2.5 percent a year, well above its long-term historical average of 2 percent a year over the past century.
Contrary to Attali's portrait of the United States becoming "Japan's granary," industry contributed the same one-fifth of GNP that it did in the 1970s.
Moreover, productivity in manufacturing rose by 3.5 percent a year in the 1980s, and absolute productivity (product per worker) remained higher than in Japan or Germany. That is not a portrait of industrial decline.
It is a mistake to generalize from cars or consumer electronics to all industry. The United States continues in the forefront of industries like aircraft, chemistry, biotechnology and computers.
And measurement of overall labor productivity is an underestimate that reflects the difficulty of measuring productivity increases in the service sector.
Its university system, the engine for intellectual supremacy, far outstrips those of all its rivals. Along with Japan and Europe, the United States remains at the forefront of the third industrial revolution -- the changeover to an information-based economy. America is also fortunate in that its prime military adversary for 40 years is suffering acute economic decline.
Other recent empires, like Britain earlier this century, have not enjoyed this advantage. Nor does the United States suffer from that other curse of empires: an imperial overstretch. It has no colonies, no restive people to tire its will or its resources. Defense spending, which took 10 percent of the nation's wealth under Eisenhower, took only 6 percent under Reagan; within five years it will be down to 4 percent.
But will the drop in the importance of military power, now that tension with the Soviet Union has eased, reduce the significance of the one dimension of power in which the United States has a clear advantage? No. To argue this not only ignores the strength of American science and culture as well as the sheer size of its economy.
It also misunderstands the role of military power in the l990s. The end of the Cold War reduces but does not eliminate the role of military force. This is amply shown by the gulf conflict; and even a reduced American security guarantee remains of value to Europe and Japan, as insurance against uncertainty.
Ironically, if others value that insurance policy more than the United States does, it may do more for American bargaining power than much larger forces did at the height of the Cold War. It is notable that in 1991 there will be few calls for the removal of American forces from Europe and Asia; rather the opposite.
The current debate between "declinists" and "revivalists" in the United States tells more about the American mood than about reality. Americans have a long tradition of worrying about decline. The founding fathers in the 18th century were already concerned. The theme returned in the 1890s with the closing of the American frontier. More recently, in the 1950s, the Soviet Sputnik satellite was seen as a sign of relative American decline, as was the oil crisis of 1973.
The latest bout of declinism may reflect a reaction to the exaggerated boosterism of the Reagan years. But, as the action over Iraq has shown, where America leads, others follow -- this year, next year and for the following generation.
JOSEPH S. NYE JR. is director of the Center for International Affairs at Harvard University and author of "Bound to Lead: The Changing Nature of American Power."