Like an M-1 tank at full throttle, the Pentagon under President Reagan's command has rolled over its budget critics with scarcely a pause or a shudder.
The President's televised appeal for a controversial tax increase this week is directly linked to his determination to continue a steady defense buildup. More federal revenues, plus deeper cuts in nonmilitary items, are necessary to hold down mounting deficits, the administration argues.
When the administration last February submitted its largest-ever peacetime military spending plan, many conservatives and traditional friends of the armed services joined those calling for less military spending in the coming fiscal year.
But as House and Senate conferees finished up their work on the $177 billion 1983 defense authorization bill for buying and developing weapons, it became clear that virtually all of the prime targets for likely cuts lived to fly, sail , and fight another day. These weapons include the MX strategic missile, the B-1 B bomber, nuclear aircraft carriers, refurbished battleships, the M-1 tank, and a host of other ''big ticket'' items.
Expert observers and those within government say the reasons for this are made up of equal parts politics and substantive considerations.
Many members of Congress agree with Defense Secretary Caspar W. Weinberger that -- mounting federal deficits notwithstanding -- military spending should be ''measured against the threat'' and not against social or economic costs. Many lawmakers also were persuaded that the US negotiating position on conventional and strategic arms reduction is enhanced by projecting a stout national defense front at this time.
But there were less lofty reasons as well, reasons that led one Republican senator to ruminate privately that ''the military-industrial complex is the one part of the economy that is alive and well when everything else is down.''
An example is the decision by House and Senate conferees to acquire the Lockheed C-5B as the prime Air Force cargo plane while buying some surplus Boeing 747s, even though the military says it doesn't want the used airliners.
A retired Navy admiral called the congressional tussle over which giant cargo plane to buy ''really a bitter and bloody cutthroat battle.''
''For defense contractors, it signals boom times . . . ,'' Dun's Business Month reports in its August issue. ''Congress seems to be moving in lockstep with the Reagan administration, toward ever bigger buys of even more advanced and costly weaponry.''
Part of the politics here is the promise of new jobs resulting from a defense buildup. ''The talk about cuts got overridden locally by saving jobs,'' says Sen. David Durenberger (R) of Minnesota.
Much has been made in recent months about the ''military reformers'' on Capitol Hill, who include such relative conservatives as Sen. John Warner (R) of Virginia (a former Navy secretary) and Sen. Sam Nunn (D) of Georgia, as well as more liberal members.
But when it came to affecting policy and the budget, the group's diversity was its weakness. Sen. Gary Hart (D) of Colorado, for example, wanted to eliminate the two new giant nuclear aircraft carriers. But he couldn't even persuade his fellow lawmakers to swap one for a less costly, oil-fueled carrier.
Earlier this year, the administration agreed to a relatively small cut in projected defense spending over the next three years. But the President now says he will not be bound by that arrangement in coming years.
Looking at the congressional action on 1983 defense spending, retired Rear Adm. Eugene J. Carroll says, ''They've just whittled at a few odds and ends.'' Admiral Carroll, deputy director of the Center for Defense Information (which provides critical analysis of Pentagon spending and programs), says total reductions amount to not much more than 1 percent.
For the most part, House and Senate conferees have restored the cuts made by the individual chambers. Little opposition is expected when the conference bill is returned for approval.
The political repercussions from recent action on the defense budget remain to be seen, but there are indications that strong congressional support for the Pentagon (like recent votes against a nuclear freeze) may not be met with approval at the polls this fall.
''A basic change is occurring in the politics of military spending,'' Common Cause president Fred Wertheimer wrote in a recent column for the Washington Post. ''The powerful coalition that has long dominated this issue still holds the high ground. But it appears headed for its first serious challenge, and perhaps for the fight of its life. . . . In 1982 candidates of all political persuasions will seriously question the military budget and whether the funds are being spent wisely or effectively.''
In a recent analysis, the Ripon Society (made up of moderate Republicans) warned that defense spending may quickly become ''the Reagan administration's Achilles' heel.''