A major critique of American defense planning was released yesterday by the Congressional Research Service, and its author warned that this country makes the same mistake as the Soviet Union by putting too many political appointees rather than professionals in key jobs.

"We sneer at the Soviets because they use political reliability as the top prerequisite for any important position, yet we are doing precisely the same thing," said John M. Collins, the senior specialist in national defense for the Library of Congress and author of the 313-page study.

Collins, a retired Army colonel and respected defense analyst whose study covered the last 37 years, says few presidential counselors in that period have had the necessary "education and experience . . . to participate effectively in the defense strategy formulation process."

But these presidential aides were nevertheless generally better prepared than most secretaries of defense in Collins' view. Of 15 secretaries, he says only three -- George C. Marshall and Robert A. Lovett in the early 1950s and James R. Schlesinger in the mid-1970s -- had previous experience in "defense concept formulation and strategy," though others such as Melvin R. Laird, Donald H. Rumsfeld and Harold Brown all had some defense background.

In Collins' view, 12 of the 15 Pentagon chiefs "found on-the-job training imperative" and "few passed the primer stage before they were replaced." About one-third of the 48 top military officers who have made up the joint chiefs of staff during the past 37 years lacked any joint service assignment in their careers before becoming part of a group that is meant to help unify defense policy.

Average tenures for top people throughout the defense community are "so short [2.4 years in the case of defense secretaries, Collins says] that even fully qualified players found it almost impossible to promulgate cohesive policies and programs, much less pursue them to successful conclusions."

"Unfortunately," the study continues, "neither the [White House] National Security Council nor State Department features a career staff that ensures continuity. The former employs foreign policy and defense professionals who depart when party affiliations of presidents change. Political appointees people the State Department, where key personnel bob in the front door and out the back at high speed."

Collins says similar turbulence affects the political appointees in the Pentagon and that "the U.S. intelligence community suffers from people problems at least as debilitating as those that plague planners in the State Department and Pentagon."

"In many cases," Collins said in an interview yesterday, "professional competence is almost disregarded and so you have to ask yourself, 'Are we so destitute for talent that we cannot select top planners that leadership feels comfortable with and that are also professionally qualified.?' We've got to be able to do that," he says or face increasingly grim prospects in defending the country and solving international crises.

The study comes as both the military services and Congress are eyeing possible reorganization of the military hierarchy as one way to improve efficiency.

But Collins says "the problem is people rather than organization. We're putting square pegs in round holes" throughout the civilian and military defense community, he says.