How to contain the bomb

On this page last Friday Robert R. Bowie, a former deputy director of the CIA , explained convincingly why the current ''nuclear freeze'' movement is not a practical method for reducing the danger of the use of nuclear weapons.

The movement itself is well intentioned. It has given a lot of people a chance to express their sense of frustration over the failure of governments to do something practical. Many people did so at the ballot boxes across the United States this week.

But, to be realistic, you and I know that even if President Reagan believed in the idea of a ''nuclear freeze'' and approached the Soviets with a proposal for negotiations aimed at getting one - nothing could come of it for years, if ever. The chances are that the Soviets would not buy it even though Mr. Reagan thinks it would be to their advantage. They would probably think it was some kind of a Washington trap or trick.

But this does not mean that there is no practical approach to the real need behind all the rhetoric of the popular movements. There is a practical approach. A lot of expert study has been going into it over the past year.

Let's start with the real need. What is it that the ban-the-bomb marchers and the nuclear freeze preachers are after? They are moved by fear that the Soviet and American governments will stumble into a nuclear war which will wipe out modern civilization and probably much and perhaps most of the human race. They want to reduce the danger of nuclear weapons being used.

The danger exists.

But what is the single most likely way in which a nuclear war might start?

The most likely scenario, and the one to be found in most studies of how a third world war might start and might then escalate into a nuclear weapons exchange, begins with a Soviet offensive aimed at the NATO front on the north German plain.

The Soviets are generally believed to have enough superiority over NATO forces to be able to break through the NATO front and head for the Rhine and the English Channel. For that reason NATO planning has long relied on short-range nuclear weapons to be used to blunt the nose of the Soviet attack - if the breakthrough should actually threaten.

There is a variation on the scenario. Suppose the Soviet advance is stalled. The Soviets might then be tempted to use a nuclear weapon to open the way for their tanks through the NATO front. That is a possibility. The only way to guard against it is for NATO to be able to retaliate instantly.

But the likelihood of the Soviets launching the attack in the first instance would be greatly reduced if the Soviets knew that in all probability their offensive with conventional weapons could and would be stopped by conventional NATO weapons. At least, the reason for NATO to be the first to use nuclear weapons would disappear if NATO could stop the offensive without using them. That in itself would be a powerful deterrent to the beginning of the war.

For years it was assumed that NATO could not produce enough conventional force to be able to stop a Soviet threat. This is of course why the NATO high command has resisted any ban on ''first use.'' It thought it might have to fall back on ''first use'' to save Europe.

Of late that assumption has been challenged. A lot of experts have done studies on what it would cost the NATO countries to build enough conventional force to stop a Soviet offensive. The first published result came last summer in the July 31 issue of the (London) Economist. The conclusion was that a Soviet offensive could be stopped with an increase of only 1 to 1.5 percent above existing NATO plans for building up NATO forces.

In mid-September this conclusion was confirmed by the best possible source. US Gen. Bernard Rogers, NATO's supreme commander for Europe, told reporters that if the NATO allies would raise their force levels ''in real terms'' by 4 percent ''by 1989 the alliance would present defenses so powerful that the Russians would be deterred.''

Existing plans call for a 3 percent increase in such force levels in ''real terms.'' So NATO's top general agrees with the back room experts that for only a relatively small further raise in NATO force levels the need would be removed for any first use of tactical nuclear weapons on the NATO side.

This is an achievable condition. It would not ''ban'' or ''freeze'' the bomb. But it would diminish the likelihood of it being used - which is more than any freeze or ban movement can do.