Cruise missile quandary: How many, where?

US and Soviet negotiators in Geneva have yet to immerse themselves in the arcane world of cruise missiles as they haggle over ways to reduce nuclear weapons in Europe. But the Brookings Institution has completed an exhaustive study of the subject, which it has just published. And it is clearly concerned by what it has found.

Noting that the US plans to deploy 464 ground-launched cruise missiles (GLCMs) in Europe to help counter the USSR's growing arsenal of theater nuclear weapons, the prestigious Washington research organization declares that ''no one knows for certain how many cruise missiles the United States should buy for military purposes or how many it should give up for political purposes.''

American defense analysts and policymakers must resolve these issues, insists the Brookings Institution, if arms control is to amount to the ''giant step'' that President Reagan proposed last month.

Reacting to the more critical sections of the Brookings Institution study, an industry spokesman familiar with cruise missiles terms them ''uneducated.'' He insists that the Pentagon is well aware of precisely how many cruise missiles ''it wants and needs.'' He says that cruise missile requirements were well established when President Carter canceled the production of the B-1 bomber in 1977 and ordered that development of the air-launched cruise missile (ALCM) be accelerated. ''To say that no one thought it out is patently ridiculous,'' he adds.

In his Nov. 18 speech, President Reagan offered not to deploy 108 Pershing II and 464 GLCMs if the Soviet Union dismantles some 600 SS-20, SS-5, and SS-4 medium- and intermediate-range ballistic missiles. Soviet President Leonid Brezhnev rejected this overture last week and renewed his oft-made call for a moratorium on the production and deployment of such weaponry.

One of the factors that helps make the President's proposal unacceptable to the Soviet Union, the Brookings Institution claims, is the administration's plan to deploy several hundred nuclear-armed, sea-launched cruise missiles (SLCMs) on general-purpose submarines beginning in 1984. The study says that SLCMs can strike Eastern Europe and would not be constrained under the President's proposal. By contrast, it notes that ''we are demanding that the Soviets dismantle all of their existing intermediate-range missiles targeted on Western Europe.''

In a 612-page report entitled ''Cruise Missiles: Technology, Strategy, Politics,'' the Brookings Institution observes that conventional and nuclear cruise missiles pose ''severe problems'' for arms-control negotiators seeking a workable system of verification. ''Given the commonality of cruise missile airframes, it will be extremely difficult to prove to Soviet satisfaction that all cruise missiles should not be counted as nuclear weapons,'' it declares.

According to the Brookings Institution, the US is planning to spend some $11 billion for ''well over 4,000'' cruise missiles, including air-, ground-, and sea-launched models as well as antiship and air-to-surface variants.

But in its view, these cruise missile programs ''are rushing forward without a well-defined conception of why some of the models are needed, without an understanding of their full significance, and without a clear assessment of whether other weapons systems might be better choices for performing some of the missions. . . .''

In the near term, the US need for an ''assured destruction capability'' vis-a-vis the Soviet Union ''does not make the cruise missile essential,'' claims the research organization. As it sees it, ballistic missiles, both land- and sea-based, as well as bombers, are quite capable of crippling Soviet society.

A series of uncoordinated technical innovations in the early 1970s transformed crude and inaccurate cruise missiles into ''much more attractive'' weapons, asserts the Brookings Institution. Among these developments were better guidance systems and small, high-yield warheads.

As a result, it claims, the civilian sectors of the Pentagon - ''research and development offices and secretaries of defense'' - virtually forced cruise missiles on the military, believing they would be ''militarily good for everything.'' Declares Richard K. Betts, editor of the Brookings Institution report: ''Cruise missile policy is a bucket of worms . . . Neither the benefits nor the disadvantages of cruise missiles are as revolutionary or as simple as either advocates or opponents originally believed.''

The Pentagon had no immediate comment on the cruise missile study.