The most realistic way of reducing the danger of general nuclear war is to eliminate the incentive for a nation to strike first, Morton H. Halperin, instructor in Economics, told the Harvard-Radcliffe World Federalists yesterday.

At present, Halperin stated, both the United States and Russia have "fast-reaching strategic resistance systems." We are not yet in the missile age, but depend for the most part on aircraft, which are vulnerable until they leave the ground, he said. This means that the ability to fire quickly is crucial.

Since the premium to strike first is so great, a nation may feel itself compelled to attack with nuclear weapons when, if it only waited a few days, it would see that such a course was unnecessary. This increases the danger of war by accident and of "preemptive war," begun in the belief that an opponent is about to strike, according to Halperin.

For example, if something suspicious is picked up on a radar screen, although it may be only a "flock of geese," a country must act on the assumption that the enemy is attacking, and launch its own offensive.

Country A may even be aware that only an accident has happened. But it must act as if it does not have this knowledge, since B will probably assume that A is planning to retaliate, and will itself attack, regardless of its original innocence.

Thus, the development of invulnerable slow reacting systems is essential, so that "both Russia and the United States will know that they can ride out an action, and that the other power can also ride out the action." This is probably "safer defense against war" than total disarmament, Halperin commented.

Halperin was a recent collaborator, together with Thomas C. Schelling, professor of Economics, on the well-known volume Strategy and Arms Control.