How ironic and unfortunate that on the morning that talks began to reduce nuclear weapons for the first time in the history of the nuclear era, The Post used its lead editorial {Dec. 7} to call for a new land-based nuclear weapons system. It may be for the wrong reasons, but Congress and the administration are right, and The Post wrong, about building the Midgetman missile.

Agreement, at least in principle, may have been reached at the summit meeting to reduce existing nuclear weapons stockpiles by 95 percent. While even the remaining 5 percent could still destroy civilization, such a level could more truly be termed a deterrent rather than a first-strike or war-fighting force.

Retention of land-based missiles in such a deterrent would be useless redundancy. There is nothing magic about a triad means of nuclear attack, despite our long obeisance to that policy. The key is survival of the deterrent. Submarine basing is vastly superior to mobile land basing for that purpose, and sea basing would have the added benefit of reducing the number of inhabited potential target areas.

Undoubtedly, The Post supports the innovative efforts being undertaken this week to reduce the imminence of nuclear destruction. In the face of those efforts, urging the building of a new land-based nuclear weapon is business as usual where vision should be offered.

JOSEPH L. MAYER Washington