Washington — The future of American arms control and strategic doctrine reaches a key juncture this week with congressional consideration of funding for the MX missile.
The post-July 4 fireworks could be especially hot in the Senate, where opponents are promising a filibuster.
The key to MX funding is likely to be a new generation of strategic weapons, which some defense analysts say will be less threatening, and a new attitude on the part of the Reagan administration regarding the limitation of such weapons, as outlined in the recent recommendations of the commission headed by former Air Force Lt. Gen. Brent Scowcroft.
There have been recent indications that President Reagan is becoming more flexible in his position at strategic arms reduction talks (START) at Geneva. ''So far, so good,'' says Rep. Les Aspin (D) of Wisconsin, a leader in the congressional effort to tie MX support to a reinvigorated arms control effort.
But proceeding with the full recommendations of the Scowcroft Commission (to deploy some MX missiles, shift arms control emphasis from missiles and other launchers to warheads, and develop a mobile single-warhead missile) also hinges on demonstrated earnestness on what has been dubbed ''Midgetman.''
The Midgetman concept involves building a one-warhead intercontinental ballistic missile (ICBM) that is roughly 30 feet long and weighs about 15 tons. The 10-warhead MX weighs in at 95 tons and stands about 70 feet tall.
The smaller missile's advocates in Congress and elsewhere are concerned that the Air Force isn't really that enthusiastic about the new idea, which many experts say could make the strategic superpower face-off much more stable. Indeed, one general concedes the Air Force is suffering ''culture shock'' from this new small-is-beautiful idea in strategic arms.
But senior Pentagon and Air Force officials insist that they have embraced the idea as their own, that they fully support the recommendations of the Scowcroft Commission, and that they will make every effort to keep Midgetman small and mobile.
''We have become very enthusiastic about the program,'' says Brig. Gen. Gordon E. Fornell, special assistant to the Air Force chief of staff for MX issues.
Congressional advocates, who are working over the administration's 1984 defense authorization request this week, aren't taking such assurances for granted. A group of them recently heard General Scowcroft describe the Defense Department as ''a little like a glacier.''
''It has been moving down the big ICBM road for a long time,'' Scowcroft said. ''There is no great love for the small missile. . . .''
To ensure that Midgetman gets beyond the draftsman's table - whether the Pentagon loves it or not - Congress is likely to tie MX production and deployment to progress on the smaller missile, carrot-and-stick fashion. It may also, at Congressman Aspin's urging, insist that the new mobile weapon not grow above a certain size.
But the total weight of a smaller missile is very sensitive to changes in warhead size, says an Air Force expert, and there are other unknowns, including a new guidance system. Some have said the missile may have to weigh closer to 20 tons, which could affect its ability to ''dash'' about in order to avoid attack.
Such mobility is the key to its survivability, experts say. And remaining invulnerable is the key to stability and making nuclear war less likely.
''The thing is to protect the mobility, and we're dedicated to that,'' General Fornell told Pentagon reporters.
Current plans envision a truck weighing 70,000 to 90,000 pounds to carry Midgetman. Nicknamed ''Armadillo,'' it would be well armored and have suction cup- or corkscrew-like devices so that it could grab onto the earth and not be tipped over by nuclear blast.
While it could be driven on highways, Defense Secretary Caspar W. Weinberger prefers keeping it on military reservations to avoid political controversary of the kind that defeated the Carter administration's race-track basing plan for MX. The Air Force figures it could spread 1,000 of the small missiles and their vehicles over 12,500 square miles and expect most of them to survive an enemy attack.
Given current technology, such a plan would be very labor-intensive. And it would be expensive.
The Congressional Budget Office says it would cost $100 billion over 20 years. The Air Force puts the figure at about $70 billion for 10 years. Both figures are well above the projected $25 billion cost of building and deploying 100 MX missiles (with the same number of warheads as 1,000 Midgetmen) in existing missile silos.
Some are urging a crash program of Midgetman development. The Air Force says full-scale development will start in 1987, with deployment beginning in the early 1990s.