Thank goodness, the Reagan administration is revising its thoughts about the MX. The decision to abandon plans to deploy the new nuclear missiles in hardened Minuteman silos over the short term is a sensible one. As critics have argued, it is virtually impossible to harden a silo sufficiently to make it invulnerable to a Soviet attack. So why spend the money?
From the time of its conception the MX has had a harebrained quality about it , and even the present administration seems to be groping for an answer. The MX came into being to close the ''window of vulnerability'' - the alleged threat which the Soviet Union will pose to US land-based missiles in the mid l980s. But now the administration has downplayed this concept. Deploying the MX in stationary silos obviously would not make the US force any less vulnerable; it might simply provide greater missile accuracy. Hence the Pentagon is going ahead with production of the MX even while figuring out what to do with it.
Many experts even question the accuracy of American or Soviet nuclear missiles under wartime conditions and therefore doubt the MX would enhance the nation's security. Indeed by making weapons more and more threatening, and in effect acquiring a first-strike capability, the United States simply escalates the arms race and heightens the risk of a Soviet first strike. This is why a further arms control agreement is so important.
It is encouraging, however, that the President and his defense aides are taking a close look at the MX system. In his determination to rebuild America's defenses, Mr. Reagan has been reluctant to make any move which might be interpreted as a weakening of this resolve. But the point is that security can only be enhanced by choosing the right weapons.
Other ''big ticket'' items also need review. The new military budget, for instance, calls for building two more large aircraft carriers. Yet these are enormously costly and seem to undercut the objective of increasing the US Navy to 600 ships for performing expanded global tasks. William Kaufmann of MIT notes that 38 of the l33 new ships required to meet this goal are associated solely with the planned two new carrier battle groups.An alternative favored by retired Admiral Stansfield Turner and others is to focus on smaller carriers and ships. The Congressional Budget Office, for its part, suggests that instead of adding two carrier battle groups the navy could refurbish its battleships and add four battleship battle groups - doing so in a shorter time and at an ultimate saving of $37 billion. The question is: does the US need large carriers for its peacetime commitments? If not, what would be better?
The B-1 bomber is another target for scrutiny. This costly plane - a fleet of 100 will run some $30 billion - is meant to replace the existing B-52 bombers. Yet the B-1 will not be on stream until 1986, only three years before the more advanced Stealth bomber is scheduled to be ready for production. Is it worth spending $30 billion for a three-year gap?Some analysts argue that the B- 52 is a wholly rebuilt aircraft and, equipped with cruise missiles, could more than adequately perform its job until the Stealth is ready.
These and many other areas still need analysis and rethinking as the military expansion goes ahead. The American people want to improve defense readiness but they also want the most rational and efficient defense possible. Giving up the plan to reinforce 40 silos for the MX missile suggests that the administration is prepared to be flexible and realistic. That is a good sign.