We've had far too much jumbled rhetoric, conflicting testimony and macho political posturing on the MX. But administration lobbying efforts nothwithstanding, the only way to truly increase deterrence is to modernize our strategic systems so that we can ensure an effective retaliatory capability in the event of a Soviet first strike. These new systems will include the Trident submarine with the D5 missile, the B1B bomber and a replacement for our aging Minuteman ICBM force. But in my judgment -- and despite the outcome of the Senate's first vote on this issue yesterday -- the Minuteman replacement should not be the MX.

The administration has bullied Congress, implying that opposition to the MX is unpatriotic and that failure to fund the missile would "knock the legs out from under the bargaining table" in Geneva. But Soviet planners are less interested in rhetoric than they are in reality. And the reality is that placing MXs in the same old silos that the Soviets have had targeted for more than 20 years would simply perpetuate the existing vulnerability of our ICBMs.

The only effective way to reduce that vulnerability is to make our missiles mobile, so that Soviet planners will not know where to shoot. Mobility, of course, is the key concept behind our submarine-based missiles, which make up over 50 percent of our nuclear forces. Not surprisingly, the Soviets fully recognize this principle and are now starting to deploy their own mobile ICBMs, the new SS24s and 25s.

The time has come to make America's ICBM force mobile as well. The mobile missile -- already well on the road to development by the U.S. Air Force -- would be a much less attractive target than the MIRVed MX and, more important, would be nearly impossible to locate for a preemptive strike. Nor would accuracy be a problem, since the mobile missile could equal the MX's accuracy.

Cost, of course, is another important factor, and a small mobile system might actually be cheaper than the MX. The administration wants us to believe otherwise, but its cost figures deal only with the price of the missiles themselves, ignoring the additional basing expenses. In congressional testimony two weeks ago, for instance, the administration put the cost of each MX missile at $74 million. But that is far less than what they would actually cost. The reason is that sticking MX missiles into the same old vulnerable Minuteman silos makes sense only if we "super-harden" those silos, so they could withstand a Soviet attack. The only alternatives would be a "launch-on-warning" or a "launch-under-attack" strategy, both of which are unacceptably dangerous.

But here's the kicker: super-hardening would cost at least $180 million per silo, bringing the actual cost of each MX missile to at least $254 million -- and that doesn't even include the additional costs of research and development or program support. And let me add that I'm not making those figures up; they were given to the Senate Armed Service Committee last week by the U.S. Air Force. Furthermore, silo hardening won't work if Soviet missiles become more accurate, as they assuredly will.

Finally, we should consider the effects of the MX on the Geneva arms talks. I don't deny that we should proceed with building new strategic systems that will bolster deterrence and stabilize the nuclear balance. But we must show the Soviets that we are willing to negotiate seriously in the area of arms control.

Lately, administration supporters have been touting the MX as a "bargaining chip." Indeed, Secretary of Defense Weinberger wrote to me on March 14 explicitly stating that "every aspect of our modernization program, including MX, is on the bargaining table" (emphasis added). Yet as Gerard Smith, CLark Clifford and Paul Warnke pointed out in a recent letter to The Post (Free for All, March 16), "the MX, if approved, will be a weapon with tens of billions spent, entrenched constituencies pressing for its continuation, if not expansion, and a bargaining chip that will have lost its ability to bargain." Exactly so. In the area of weaponry, there is a long history of supposed "bargaining chips" suddenly becoming nonnegotiable once they are approved. There is no reason to think the MX will be different.

In sum, the small mobile ICBM is superior to the MX by almost every measure: it is less vulnerable and costly; more stabilizing and amenable to arms control. For all these reasons, I will oppose MX missile appropriations and support the small, mobile alternative. It would give us a deterrent that is stronger, not weaker, than the one proposed by the Reagan administration.