For two years, Reagan administration officials have been insisting that increased defense spending must be measured ''against the threat,'' that is, against what the Soviet Union is doing militarily.
Curiously, however, they appear not to have been as forceful in this regard as they might have, and this could affect their standing on two important fronts this week: in Congress, where the nuclear freeze proposal comes up again, and in New Delhi, where ''nonaligned'' countries are meeting and much criticism of the United States is being heard.
Hawks note that this year's Department of Defense and Joint Chiefs of Staff posture statements contain far less detail on Soviet capabilities than in past years. There are significantly fewer tables and estimates on the balance of power (13 this year compared with 78 in 1982). Some advocates of a military buildup (like Senate Armed Services Committee chairman John Tower (R) of Texas) have been urging the White House to declassify certain intelligence information on the Soviet buildup. This advice is being closely listened to within the administration.
In an attempt to answer these critics, Defense Secretary Caspar Weinberger Wednesday made public this year's version of ''Soviet Military Power,'' a report analyzing in considerable detail the size and shape of Moscow's defense buildup over the past two years. In essence, it updates a similar report made 18 months ago.
Significant new items are expected to include: flight testing of a new long-range Soviet strategic bomber designated ''Blackjack''; first tests of a new solid-fueled ICBM similar to the MX and testing of a new small mobile strategic missile; completion of the third Kiev-class VTOL (vertical takeoff and landing) aircraft carrier with the fourth soon to follow; development of a larger carrier with catapults and arrested landing systems to accommodate bigger aircraft; deployment of new T-80 tanks in Eastern Europe; development of two new fighter aircraft; final testing with combat troops in Afghanistan of a new ground-attack aircraft similar to the American A-10; deployment of the second Kirov-class nuclear-powered guided missile cruiser; and construction of a new class of large, conventionally powered cruisers.
What particularly troubles Secretary Weinberger and other officials is that Soviet armed forces are ''increasingly structured for offensive use,'' especially in strategic missiles (some of which have a refiring capability), tactical aircraft, and major combat surface ships and submarines. They also lament the loss, over a long period, of Western military facilities to the Soviet Union in some parts of the world (South Yemen, Ethiopia, Libya, and Vietnam).
As reported recently, questions have been raised within US intelligence agencies about the rate of Soviet military growth over the past half-decade. The rate of growth may have been a bit slower than earlier thought, and this was one reason Soviet military strength was played down in Weinberger's annual report to Congress and the President's State of the Union message.
''We said basically they should avoid this issue until we finished straightening it out,'' confided one senior Soviet specialist within the government.
But intelligence officials are quick to distinguish between rate of Soviet growth and overall military capability, especially the addition of new weapons to the Soviet arsenal.
''Estimated dollar cost of Soviet military investments in 1982 (research, development, testing, and procurement of weapons as well as military construction) were roughly 60 percent more than ours and roughly $500 billion more than those of the US during the past 10 years,'' Richard DeLauer, undersecretary of defense for research and engineering, reported recently. ''This significant asymmetry starkly focuses the potential world security problem of the 1980s and 1990s because military investments provide a return for 20-30 years.''
''The large Soviet research and development effort, coupled with observed expansion in military production facilities, suggests that the dollar costs of Soviet military procurement may soon resume their historical growth,'' warns the Pentagon in Soviet Military Power.
Intelligence agencies and the military services traditionally have been reluctant to release classified data on Soviet military capabilities. Making public such information could compromise intelligence sources and methods and indicate how the US is trying to counter new Soviet weapons.