Suppose that it were possible to increase the military effectiveness of a battlefield weapon and, at the same time, reduce substantially the number of civilians who would be killed by its use just because they were unlucky enough to live near where the war was taking place.

Suppose, further, that the weapon were designed to stop a massive invasion by enemy armor that might otherwise roll, in blitzkreig fashion, across democratic Europe and the territory of our principal allies.

Suppose, finally, that in addition to the weapon's ability to help blunt an invasion of Europe and save thousands of innocent civilian lives, it was safer, had increased range and better security and replaced older weapons on a less than one-for-one basis--so that the total number of weapons would actually decline.

Neutron weapons, which President Reagan has decided to produce, have precisely these characteristics. Moreover, they have a crucial characteristic that is more important than anything else about them: they would reduce the likelihood that, even in a crisis, the Soviets would be tempted to launch an attack on our European allies. They thus promise to add to the credibility of our deterrent; and because they do that, they actually reduce the likelihood that nuclear weapons would ever be used in a European war.

It is ironic that much of the opposition to the neutron weapons is based on the belief that they are immoral--despite their role in deterring war while making the Western democracies safer for individual liberty and moral expression. The explanation lies in the abundant misinformation about neutron weapons, some of it innocently based on ignorance of the facts, but most of it deliberately disseminated by a well-orchestrated propaganda campaign based in Moscow. Thus the president's decision to proceed with the production of neutron weapons for stockpiling on U.S. territory was bound to be controversial, especially in Europe, which has been the center of a Soviet propaganda campaign that began in the last administration and that exploited both European fear and an unfortunate impression of American indecisiveness.

The president's decision to produce and stockpile neutron weapons on U.S.territory is intended to strike a prudent balance between European sensitivities, on the one hand, and, on the other, the necessity to make difficult decisions affecting U.S. forces on their merits.

The making of those decisions cannot be turned over to even our closest allies, although any ultimate deployment of neutron weapons to any country would come only after consultation with the countries affected.

In the meantime, it is possible that European attitudes toward neutron weapons will evolve, that a clearer understanding of the case for their deployment will emerge in Europe despite Soviet efforts to misrepresent our purpose and to obscure the facts.

The crucial facts are these:

1. A massive Soviet buildup sustained over many years has turned the European theater balance against the West, requiring the modernization of NATO's deterrent forces, as well as of our own capability to deter Soviet threats in other theaters.

2. A more certain NATO capability to blunt a Soviet invasion of Europe will strengthen our ability to deter attack there and lessen the likelihood of either conventional or nuclear war elsewhere.

Neutron weapons are more effective and would do less unintended damage to civilian populations than the weapons they replace.

The unrelenting Soviet buildup of the last decade flies in the face of the Soviet claim to desire detente with the West; it makes a mockery of the indignation with which the Soviets have attacked this decision to protect our deterrent.

There are those who worry that the neutron weapon, because it would not entail massive civilian fatalities near the battlefield, is more likely to be used than the weapon it replaces. The logical conclusion of this reasoning is that we should make our weapons as indiscriminately damaging as possible -- so that we would be deterred from using them. That is not the sort of deterrence that will keep the peace.