Secretary of State George Shultz and Stephen S. Rosenfeld both wrote {op-ed, Dec. 15 and Jan. 8} that the credit for achieving the INF Treaty and any potential further reductions in nuclear arms goes entirely to President Reagan. He was never, we read, a "nuclear cowboy," and "the Freeze and peace movements have been rendered marginal." This is as close to a rewriting of history as can be imagined. So, a little glasnost for the record.

It was Mr. Reagan who roughly quadrupled spending on bizarre civil defense plans and allowed T. K. Jones to pronounce citizens with "a shovel" and some dirt safe from nuclear war. Only citizen outrage and ridicule, and then congressional action, curtailed this madness.

It was Mr. Reagan who persisted with a campaign to get 200 MX missiles with 2,000 first-strike warheads. He argued that U.S. ICBMs were in a "window of vulnerability" and then placed the MX in fixed silos. Again, only a massive grass roots campaign to "Stop the MX Missile" and, finally, congressional action put a cap on the MX at 50 missiles.

Again, it was Mr. Reagan who doubled spending for strategic nuclear weapons, bringing back the B-1 bomber that had been killed during the Carter years, and adding about 5,000 new nuclear warheads to the U.S. arsenal. It was Mr. Reagan who resisted the discovery of a nuclear winter by Carl Sagan and others. Again, only after a massive public outcry and mounting scientific evidence did the administration permit the Defense Department to proceed with its own studies of the nuclear winter.

As for nuclear confrontations and threats, again it was the Reagan administration that, through Gen. Bernard Rogers of NATO, threatened the use of cruise missiles against Libya.

Mr. Reagan is also the first U.S. president not to seek a comprehensive test ban, despite an 18-month Soviet moratorium on nuclear testing and clear U.S. public opinion in favor of such a move. Mr. Reagan has increased plutonium production in the United States, ignored the hazards at nuclear weapons production sites (until the public outcry was irresistible) and pushed for a -- frankly, crazy -- nuclear-pumped X-ray laser as part of his Star Wars plan, even while claiming the program was non-nuclear.

As it turns out, we in the peace movement and allies in the scientific, business, medical and other communities have been right all along. And it was we who helped push Mr. Reagan to the summit. An uphill struggle, indeed.

Now, Secretary Shultz and Mr. Rosenfeld would have us believe that the INF Treaty -- which eliminates 2,000 out of 50,000 nuclear warheads -- proves that, all along, President Reagan was a nuclear pacifist; those of us who spoke out loudly for a freeze and then for reductions in nuclear weapons were useless and deluded.

Sorry, the record doesn't support that contention any more than it does Mr. Reagan's ignorance and peaceful intentions during the Iran-contra affair. As for the marginality of the peace movement, Mr. Rosenfeld seems to accept that view simply because the reporting of The Post on peace activities is woefully inadequate. Remember all those presidential candidates complaining about being confronted with the comprehen- sive test ban and the Trident D-5 missile in Iowa? Or the STARPAC debate, where Sen. Al Gore made news by being the only Democratic hawk? Could the peace movement have played some role in that? Or was it all part of Mr. Reagan's secret plan for peace?

ROBERT K. MUSIL

irector of Communications and Education

Committee for a Safe Nuclear Policy/Nuclear Weapons

Freeze Campaign

Washington