Washington — More significant than the immediate debate over the size of President Reagan's defense budget may be the broader issue of military posture.
Do the proposed Pentagon programs fit together in a way that clearly outlines national security needs and the policies necessary to meet those needs?
As expected, US Defense Secretary Caspar W. Weinberger's military policy and strategy report to Congress for the five-year period through 1987 is receiving mixed response.
The administration contends that its long-range plans take into account the realities of big-power confrontation and geopolitical instabilities. More spending is envisioned in all categories, but the conventional and strategic nuclear programs are carefully designed, officials say.
For all the rhetoric before and after the 1980 presidential election, Mr. Reagan's defense posture differs in degree rather than in major substance from that of President Carter.
''Seventy-five percent of what they're doing is an acceleration of what (former Defense Secretary) Harold Brown was doing,'' says William Kaufmann, an MIT political scientist who played a key role in formulating defense policy statements under five Republican and Democratic defense secretaries. ''In that sense, it doesn't represent any drastic departure from strategy and even force structure.''
Mr. Weinberger concedes as much when he says, ''We are, to a greater extent than we would like, the prisoners of our immediate past.''
When he writes that the first goal of defense strategy ''must bring to a halt the further expansion and consolidation of the Soviet military empire,'' he echoes Harold Brown's report of a year ago.
But a more muscular posture is assumed when Weinberger says: ''Even if the enemy attacked at only one place, we might choose not to restrict ourselves to meeting aggression on its own immediate front. We might decide to stretch our capabilities, to engage the enemy in many places. . . .''
Still, Weinberger insists that this will increase deterrence rather than provoke a fight: ''It is likely to increase the caution of the Soviet leaders in deciding on aggression.''
As detailed in the Weinberger report to Congress, major emphasis is to be given over the next five years to increasing conventional force strength and especially mobility. This desire to ''project power'' into many parts of the world accelerates Mr. Carter's effort to respond in such areas as the Persian Gulf.
''First, we must have a capability rapidly to deploy enough force to hold key positions, and we must be able to interdict and blunt a Soviet attack,'' the report states. ''It is the purpose of this capability to convince enemy planners that they cannot count on seizing control of a vital area before our forces are in place, and that they cannot therefore confront us with an accomplished fact which would deter our intervention.''
This is in line with earlier US military positions. The difference is that it is spoken in harsher tones, and with more guns, ships, tanks, and planes to back it up.
''The thrust of the programs initiated by President Carter remains the same, '' says Sen. David Durenburger (R) of Minnesota in his own 200-page study, ''America's Defense: A Plan for the 1980s.'' ''Both administrations proposed enormous budgets for the five-year period.''
Senator Durenburger notes, however, that there is an important difference in the assumption about the length of a military confrontation between the US and the Soviet Union. The Carter administration assumed that such a fight would be over in a matter of weeks or quickly escalate into nuclear war. Reagan planners assume that a conflict could last six months or longer, perhaps as a series of actions in different regions.
The fact that there has not been a cleaner break with past policy has upset some conservatives.
In reviewing the administration's first year, the Heritage Foundation (which played a major role in the transition and forming of the Reagan White House) said the administration ''has provided the tough words (but) has not provided the policies and programs necessary to meet US national security requirements.''
William Green, Heritage Foundation defense analyst, describes the Weinberger defense posture statement as ''the weakest one I've seen in years.''
A senior government defense analyst with many years' experience in the military says Weinberger's posture statement is ''going to be in terrible trouble on the Hill, because it's not thought through very well,'' ''From a macro standpoint, it looks like the pieces don't fit.''
''To change the forces we inherited takes time; we can alter them only incrementally,'' Weinberger said in his report to Congress. Given lawmakers' present concern over deficit and bipartisan agitation for defense cuts, that incremental change may take longer than the administration plans.