Significant changes are occurring in United States military posture - and will continue to occur regardless of the outcome of congressional debate over the size of the 1985 Pentagon budget.
Among these changes: the arming of ships and submarines with nuclear-tipped cruise missiles; new and varied means of attacking satellites in space; rethinking of the role of US forces abroad; and a new generation of ballistic missiles that will accelerate changes in US strategic doctrine.
All involve fundamental issues impacting on the purpose of US military might as the legacies of World War II and the early years of the nuclear arms race recede.
* The proliferation of nuclear SLCMs (sea-launched cruise missiles) - scheduled to begin in a matter of days - will expand the threat of atomic attack from most of the earth's surface.
These Tomahawk missiles - impossible for an opponent to distinguish from their nonnuclear variant - make any ship or submarine a potential nuclear threat. They also increase the chances that any major engagement at sea could quickly become a nuclear battle. Congressional efforts to halt such weapons have not succeeded.
* Developments in ground-based lasers (now being tested) and antiballistic missiles (of the type successfully fired last week) indicate the potential for putting all satellites at risk. This could disrupt the principal means for anticipating attack as well as impede an opponent's ability to direct sea and land battles from space.
This will happen whether or not lawmakers limit ASAT (antisatellite) testing and even if the Reagan administration proposes some kind of limited ASAT treaty. The administration is determined to continue testing the Air Force's new aircraft-carried antisatellite rocket in any case.
* The question of whether to continue maintaining some 330,000 US troops in Europe has less to do with budgets than with issues of strategy and potential threat. Is the US trying to do too much with limited military resources, as Sen. Sam Nunn (D) of Georgia warns? Ought policymakers to be concentrating more on other parts of the world like South Asia, Latin America, and the Far East, as some military analysts suggest?
''I'd like to see fewer deployed troops and more mobile strategic reserves,'' says Michael Vlahos, director of security studies at Johns Hopkins University's School of Advanced International Studies.
''We're dealing with a fracturing world,'' says Dr. Vlahos. ''We have to be very, very flexible, and we're not.''
The troops in Germany and other parts of Western Europe will not be heading home anytime soon. But pressure is building to reduce US commitments to NATO, particularly in light of new indications that the US is bearing more than its fair share of the defense of Europe.
In a report to Congress made public this week, Defense Secretary Caspar W. Weinberger said some European countries are doing ''far less than seems equitable'' in their contributions to common defense.
Still, warned Secretary Weinberger, ''congressional restrictions designed to 'punish' inadequate allied performance or to force allies to compensate for a diminished US effort can jeopardize our endeavors to increase allied defense contributions.''
* For all the criticism of the MX missile and its close calls on Capitol Hill , this new generation of intercontinental ballistic missile - the first for the US in over 20 years - is proceeding very well toward deployment. Flight testing has gone better than the Air Force had anticipated. Funding for all 20 flight tests is virtually assured, as is the money for initial missiles in silos to begin two years hence.
''It's important to be able to say up front that this thing works,'' said Brig. Gen. Gordon Fornell, the Air Force officer in charge of the MX program. ''Overall, the missile is performing absolutely marvelously. I anticipate that we'll be able to go to deployment on schedule without any of the glitches we've had on previous programs.''
The first 10 of 100 MXs in existing silos in Wyoming and Nebraska are to be deployed in December 1986. The Air Force wants to buy a total of 223 missiles, the extra 123 for spares and continued testing. Congress last year agreed to fund the first 21 missiles.
The other new nuclear ballistic missile in the US arsenal - the Pershing II - already has begun to be deployed in West Germany. Even though it continues to have some problems (the most recent test missile failed to hit its target), congressional efforts to halt production have not been successful.
Both the Pershing II and the MX are much more accurate than their predecessors, as will be the new Trident II submarine-launched missile and - if it proceeds beyond the research stage - the mobile, single-warhead ''Midgetman.''
This will provide the capability to launch attacks on ''hard targets'' such as missile silos and hardened command facilities.
Proponents say this moves strategic doctrine away from ''mutual assured destruction'' and the targeting of population centers. Critics warn that it could make the launching of a nuclear attack more tempting.