James Woolsey {"Strange Strategic Bedfellows," op-ed, Nov. 3} sometimes has excellent ideas on national defense. But his opposition to a ballistic missile flight test ban is not one of them. It seems to us that he hasn't thought the matter through and has come to a conclusion that is profoundly wrong.

His objection to a ban says, in essence, that missile tests are good things. They are, when they lead to better and more reliable U.S. missiles. But when they lead to quicker, more lethal and more reliable Soviet missiles, tests are not good things.

On balance, the danger from continued testing clearly outweighs the benefit.

If the Soviets exploit the opportunities testing gives them, they can eventually become quick and accurate enough to neutralize our ICBMs and bombers. We would be driven down to a one-armed nuclear deterrent: our missile submarines. Conceivably, a single cataclysmic Soviet antisubmarine breakthrough could then end the U.S. deterrent entirely.

We would have a similar first-strike threat against the Soviets, of course. But since we are not a first-strike nation, this would be of no use. Our purpose is to deter a first strike, not to commit one. Deterrence requires us to prevent the Soviets from making their weapons quicker and more accurate, and the best way to do this is the flight test ban.

What about reliability? Flight testing makes missiles more reliable, and Woolsey argues that reliability makes the U.S. nuclear deterrent more credible. In theory, he's right. But he is looking at only one side of the coin: what American missile reliability can do for us. We must also ask what Soviet missile reliability can do to us.

Perfect reliability means a perfectly reliable Soviet first strike against our silos and bombers. Suppose both sides had perfectly reliable, perfectly accurate and very quick weapons. If the Soviets fired first, their reliable weapons would turn our reliable weapons to ashes.

Given the appropriate antisubmarine breakthrough, the Soviet aggressors would succeed; they would be safe from our retaliation, and we would be at their mercy. Their risk would be near zero. So would our deterrent.

In contrast, if weapons on both sides were of uncertain reliability because they hadn't been tested for many years, deterrence would be restored. The aggressor would be deterred because he could never count on a successful first strike. He would know that some of his weapons would fail, some of his victim's weapons would survive, and some of those surviving weapons would annihilate the aggressor's homeland.

Woolsey advocates another solution: the small mobile ICBM, Midgetman. There is much to be said for mobile ICBMs, but they are not a cure-all for our strategic problems. In time, there is a significant danger that they willbecome vulnerable to very quick or verysmart Soviet missiles or to other countermeasures.

The flight test ban offers a higher confidence route to ICBM survivability. By stopping improvements in Soviet ICBM accuracy, the flight test ban would let us protect our ICBMs simply by hardening our silos without buying a single new missile. And measured in dollars per survivable warhead, U.S. Air Force figures suggest silo hardening is less than half the price of Midgetman.

The flight test ban and Midgetman need not be incompatible. The ban works best if it allows a single tightly limited exception for development: testing of a small mobile ICBM on both sides. Midgetman itself would be more secure under such a regime, since the ban would prevent the Soviets from testing advanced quick/smart missiles to threaten our mobile ICBMs. With the flight test ban plus Midgetman, America could have secure silos and secure mobile ICBMs: the best of both worlds. -- Les AuCoin and William Colby Rep. AuCoin (D-Ore.) is a member of the House defense appropriations subcommittee. William Colby served as director of the Central Intelligence Agency in the Nixon and Ford administrations.