Give President Bush credit: He had a golden opportunity to begin the process of making a "peace dividend" a reality, and he seized it. This is the best news in a long time.

By his dramatic initiative to make major reductions -- on a unilateral basis -- in many categories of America's nuclear arms stockpile, Bush will get credit in the history books for generating the first real "peace dividend" of the post-Cold War era.

Never mind that Bush may have been motivated by concerns that in an unstable Soviet Union, its nuclear weapons might fall into the wrong hands unless both the United States and the Soviets get rid of them in an organized manner. That's a legitimate goal in itself.

Never mind that Bush is anxious not to let the Democrats upstage him with a bigger peace dividend. "The peace dividend I seek is not measured in dollars but in greater security," he said in his speech to the nation.

The important thing is that Bush let the "peace dividend" genie out of the bottle: Inevitably, the world now is -- happily -- on its way toward spending less on military hardware and programs.

Bush's initiative gives new force and scope to a bolder proposal independently worked out at the International Monetary Fund to cut global military outlays by $141 billion to $183 billion on the premise that "nobody has enemies now." This will be presented to the annual IMF/World Bank meeting in Bangkok in a few weeks as the key to solving the Soviet Union's massive economic crisis.

For the Soviets, compliance with Bush's proposal that they match the U.S. nuclear arsenal reductions provides a vehicle for Gorbachev and Yeltsin to begin shucking the Soviet Union's miserable economic past and thereby achieve a major improvement in the Soviet standard of living.

For the past 45 years, the Soviets paraded under a superpower label, disguising a per-capita income no better than that of a Third World economy. They spent their riches, including (according to recent news stories) much of their gold, on their military machine and sputniks. But they couldn't make a telephone system that works or keep meat and groceries on the shelves, except for the military and bureaucratic elites.

For the United States, which has been hobbled for the same 45 years by a self-assumed responsibility for providing a security umbrella for its friends in Europe and Asia, a real peace dividend would offer a great chance to regain the competitive edge it has lost to Japan and Germany.

Like the Soviets, the United States spent its money on arms and flashy space stunts. But while we had men on the moon and hundreds of thousands of troops in Japan and Germany, the Japanese were selling cars and VCRs, and the Germans cleaned up on less visible machinery and equipment. Meanwhile, America's bridges were falling down and its highways crumbling.

Many experts feel that Bush now has initiated an unstoppable force and provided the Democrats with an opportunity to launch a peace dividend initiative of their own.

Brookings Institution political analyst Thomas Mann predicts that the Democratic push for a more rapid defense build-down will unfold in stages. Not much is likely to change for fiscal 1992, but Mann forecasts that next year, as planning begins for fiscal 1993, the Democrats will try to unravel their 1990 budget agreement with Bush in three steps.

First would be a plan for some kind of tax reduction, even if minimal, for middle-income taxpayers, whom the Democrats need to re-attract. Second would be proposals for further cuts in specific defense programs, perhaps the B-2 Stealth Bomber and Star Wars.

And third, there would be "some element" of the peace dividend reserved for deficit reduction. "The Democrats feel this kind of program will have political appeal and at the same time be credible. It's not clear how many dollars they can save, but even if they don't achieve {what they set out to do}, they then will have something to talk about in the {1992} campaign year," Mann said in an interview.

To be sure, success isn't ensured: Bush retains great personal popularity, and considerable bipartisan fear remains among citizens that defense cuts may leave us too exposed. Many Democratic politicians are still gun-shy of the proven ability of the GOP's TV sound-bite specialists to hang the "peacenik" label on them.

Beyond that, arms-weapons salesmen still have political clout. And Bush doesn't want to complicate the short-term problems of the U.S. economy, still in recession, by collapsing the American arms and munitions industries overnight.

Yet, the feeling grows in Washington that Bush has started something he can't control. The net result has to be better than the crazy path toward mutual annihilation the world has been on since the end of World War II.