Stephen S. Rosenfeld's column entitled "Weinberger's Alarm Bell" (op-ed, Nov. 5) contained some misconceptions of both the history of U.S. deterrence policy and my own position.

Rosenfeld writes of a growing "crisis of deterrence" -- a fear that the growth of Soviet military power would render our deterrence ineffective. There was a crisis of deterrence, but not within the past decade as Rosenfeld suggests. The crisis of deterrence occurred in the late 1950s as the United States came to realize that relying solely on a strategy of massive nuclear retaliation was not a credible deterrent to the wide range of nuclear and conventional attacks which the Soviets were developing the capability to conduct.

To restore credibility to our deterrent, the Kennedy administration introduced the strategy of flexible response. Every administration and every secretary of defense since has reconfirmed that strategy. Flexible response does not require American strategic superiority; it does require that we maintain a nuclear balance with the Soviet Union. This goal -- maintaining a balance rather than seeking to reestablish superiority -- is the basis of our strategic modernization program.

At the recent press conference to which Rosenfeld refers, I pointed out that in order to maintain deterrence in the future, we need to take steps now to modernize our aging forces and to offset the steps which the Soviets already have taken and continue to take. I noted that if we do not modernize our arsenal now, as the Soviets have been doing for more than 20 years, at some time in the near future we will lose the capability to retaliate effectively -- and therefore to deter credibly.

The facts of the matter are that, as I stated, we did effectively freeze our nuclear force levels in the 1970s. The Soviets, however, increased their force levels dramatically during this period. It is true that over the last 10 years we modified a limited number of existing warheads on Minuteman III missiles. In the same period of time, however, the Soviets introduced 10 variants of three new types of ICBMs. Their current force of 1,398 ICBMs now includes 308 new SS19s (with six warheads each) which are capable of destroying our ICBM force in its silos.

From 1966 to 1981, we did not build a single new ballistic submarine, but in the same time frame the Soviets built 60 such submarines. By the time the first B1 bomber enters the U.S. force, our newest B52 bomber will be a quarter of a century old. Meanwhile, the Soviets already have deployed a Backfire bomber force over twice as large as our projected B1 force and are testing a modern heavy bomber even larger than the B1. They have also spent billions acquiring a strong air defense against our bombers. We have built no such defense against air attack by them.

The result of this pattern of unilateral American restraint is that today three- quarters of our warheads are carried on launchers that are 15 years old or older, and 75 percent of the Soviet warheads are on launchers five years old or less. Without force modernization, we will be dependent on aging and increasingly vulnerable forces to deter the Soviets from using or contemplating use of their more modern and flexible forces. These are not "scare tactics" -- these are facts. These are the reasons why we must modernize our deterrent forces.

But force modernization need not mean force increases. In fact, we hope to decrease significantly the nuclear forces of both the United States and the Soviet Union. Because of President Reagan's proposals, we are now negotiating with the Soviets for substantial reductions of the strategic nuclear forces of both sides. Because of President Reagan's proposals, we are also negotiating for the elimination of a whole class of intermediate-range nuclear missiles.

Nor does force modernization mean we have entered any "precincts of 'war-fighting,' 'protracted war,'" or similar slogans which are usually used to discredit our policies. Force modernization means only regaining an effective deterrent -- nothing more and nothing less -- and nothing is more important for our security -- present and future.