IT'S ONE OF OUR CHARMS as a nation that historically we're unprepared for war, every time. Americans are very good at battle, Vietnam notwithstanding. But traditionally, we've preferred not to think about it during peacetime. When the threat dissipated, armies were made to stand down and the muskets allowed to rust.

So it is ironic that having transformed ourselves in the past 40 years into a warrior nation -- with a large permanent force and an enormous defense industry -- there seems every likelihood that we'll be caught flatfooted should war come again.

At a time when the American military should be riding high on a tide of cash and resurgent public esteem, it finds itself in remarkable peril.

The salad days of huge budget increases are finished, hooted down by a Congress obsessed with red ink. Even its staunchest enthusiasts -- such as Sen. Barry Goldwater (R-Ariz.) -- believe the Pentagon leadership should be turned on its head. In a steady parade, its most cherished suppliers, from General Dynamics to General Electric, find themselves in the criminal dock and in the public doghouse, accused of exploiting the recent buildup.

After 10 months of scrutinizing the American defense industry and its military customers -- from the aircraft plants of southern California to the tank factories of Michigan -- it seems irrefutable to us that the military- industrial complex is in such a mess that reformist tinkering is unlikely to yield anything resembling a rational method for arming America.

Perhaps there's enough national outrage now to force some of the common-sense prescriptions that have been suggested and ignored for decades. But it may be that no enterprise fattened on $300 billion a year can better provide an honest bang for an honest buck until the epiphany of catastrophe -- dead men and smoking wreckage -- jars the nation sufficiently to set things right.

Despite President Reagan's $2 trillion rearmament binge, the renaissance of the American military is incremental at best. For example, although the Pentagon in Reagan's first term nearly doubled its spending on missiles, the arms industry delivered only 6 percent more missiles than it did during President Jimmy Carter's term. A group of former defense leaders -- most of them conservative -- warned last month that the armed forces will shrink by as much as one-third in the next few years, or else return to the kind of "hollow," toothless military Reagan denounced in 1980.

Clearly, something is askew in the way we now outfit our armies.

For many military and industrial leaders a major war with a powerful enemy is an abstraction -- it simply seems unreal. Brushfire battles are conceivable -- a firefight in Grenada, a dogfight in Libya's Gulf of Sidra -- but flinging ourselves against two dozen Soviet divisions in Germany's Fulda Gap seems beyond comprehension. Perhaps it's because for 40 years we've built thousands of nuclear weapons, each assembled with the premise of inaction.

At any rate, there's a prevalent ethic, largely subconscious, that the deterrent effect of weapons is more vital than their combat capability. It doesn't matter if the stuff works as long as we demonstrate resolve by spending lots of money on it. The saber's rattle is more important than the hone of its blade.

Consequently, we tolerate a vast military bureaucracy that doesn't seem to have much to do with fighting wars. And that bureaucracy has accepted shoddy or ill-conceived or absurdly fragile weapons from defense contractors who, as Pentagon inspector general Joseph Sherick put it, "salve their conscience (by saying), 'Well, we'll never have a war, and we won't use that, and if we do, we'll always fire 10 of them anyway.'"

The result is a force entangled in the double helix of spiraling costs and complexity.

A single fighter plane costs $50 million; when a squadron of 24 fighters moves to a new base, 29 large C141 transport planes must lumber behind, lugging support equipment and mechanics. An hour's flying time for a new B1 bomber costs $12,000; a squadron of 16 B1s will need 84 crewmen and 1,493 mechanics and other handlers.

Virtually every major weapon system is so complex that it depends in some measure on industry to keep it running and fix it when it breaks. A decade ago, the Navy relied on contractors for 30 percent of the complex repair work on computers and other aircraft electronics. By 1984, that percentage had doubled.

This pricey, delicate construct has been encouraged by the defense industry -- and why not? The spree of the last five years has meant record profits, virtually zero federal taxes and a tacit guarantee of big bucks for years to come. Aerospace sales this year are expected to break the record set at the peak of the Vietnam War. Regardless of the state of national security, lots of people have gotten rich. The lowest annual pay for the chief executive among the top-10 defense contractors is just under a half-million dollars.

The Pentagon bosses stoutly maintain that everything is fundamentally hunky-dory: True, 45 of the top 100 defense contractors are under criminal investigation, but only because more enforcers have been unleashed. The $7,000 coffee pots are aberrations in a system that basically works well; to the extent that it was flawed, Caspar W. Weinberger pushed through the necessary reforms years ago. Today's bad press is largely a public relations dilemma.

Unfortunately, it just isn't so. In moments of candor, some senior Defense Department strategists acknowledge as much, as Assistant Secretary James P. Wade Jr. did last month in a 45-page white paper which concluded that the system of buying weapons is "ponderous, inflexible and so layered as to make it virtually impossible to maintain accountability."

Without question, much of the blame for the current morass can be dumped on the legions of reformers -- notably those with Rep. or Sen. in front of their names -- who have done as much as anyone to bollix things up. Congress tacks on an estimated $10 billion each year in extra "impediments" -- purchases or restrictions not requested by the Defense Department.

Two dozen congressional committees and 40 subcommittees oversee the Pentagon, which fields more than a half-million telephone inquiries from Capitol Hill every year. The legislative branch meddles in the military to an extent unimaginable in other Western democracies.

In like fashion -- and in part because Congress demands it -- Pentagon hectors industry. Government specifications for the purchase of a mousetrap run 200 pages; 80 pages are devoted to buying hamburger meat. One aircraft engine maker has 330 Air Force watchdogs in a single plant. Because of Pentagon paperwork, that plant takes 17 days to prepare a military engine for delivery, compared to 26 hours for commercial engines.

The Defense Department has 54,000 people doing its shopping, collectively spending $28 million an hour. The bureaucratic sea in which they swim is so vast that even Pentagon veterans can't begin to comprehend it. To cite one simple example, when the Army wanted to build a successor to the venerable jeep, the service had to involve 63 different agencies and military commands, from the Army Soldier Support Center to the Air Force Air Weather Service.

Thus, it's another irony that as a society we are more indulgent of the defense industry than any other sector of the business world. That may seem an absurd assertion to the guys being beat over the head -- sometimes unfairly -- for $600 toilet-seat covers. But in fact we coddle the arms makers, effectively leaching out many of the normal risks of doing business. Taxpayers foot the bill for everything from industry research -- even if it doesn't yield any military benefit -- to the plants and tools used to build military products. F16 fighters, C130 cargo transport planes and M1 tanks all are built in public buildings.

It's the kind of lenience -- a permissive willingness to look the other way -- that allows a U.S. contractor at the Indian Ocean naval base on Diego Garcia to collect half of a maximum-allowable bonus even for shoddy work rejected by the Navy. Virtually none of the big contractors are permitted to go out of business -- incompetence or criminal gouging notwithstanding -- because of a conviction that the defense industrial base must be preserved.

So what have we received in return for this golden safety net woven beneath the industry? Some impressive firepower, to be sure. The wizards of the arms industry have given the United States the most sophisticated arsenal in the world. Anyone who has ever stood on the bridge of an aircraft carrier during night operations or watched a battalion of M1 Abrams tanks sprint across the German plains knows that neither American warriors nor their weaponry should be underestimated.

What remains to be seen is whether the United States can continue to afford enough $50 million warplanes to offset the kind of unspeakable losses that would occur in the first two weeks of European combat. Also unanswered is how that sophisticated arsenal -- with 5,000 parts in a single fighter-plane fuel system -- would perform in the chaos of war.

The industry also has given us plenty of heartburn. Dud missiles, fighters with cracked tails, military transport planes with wings that threaten to fall off -- "crappy work," as former defense undersecretary Richard D. DeLauer described it. And indictments and guilty pleas and jail sentences and endless mea culpas. An audit of 216 defense contracts last year found evidence of fraud in 10 percent. Though undoubtedly confined to a minority, the industry is riddled with a pernicious subculture of greed which in national defense, as one judge observed, is tantamount to treason.

So what to do? While almost everyone agrees there's an illness, few concur on the cure. In fact, virtually every well-intentioned prescription flatly contradicts other prescriptions espoused by equally well-intentioned reformers.

Thus, one zealous reformer says that we're not adequately testing our weapons, that we're buying before flying, that we're ending up with turkeys that can barely fly at all. Yet another says, just as ardently, that it already takes far too long to develop new weapons -- 20 years for the M1 tank -- so that technology is obsolete before it reaches the battlefield.

Similarly, one can legitimately argue that the Pentagon does a miserable job of policing its contractors (one government auditor in Texas spent three years in a defense plant and was never allowed in the accounting department). But one can also contend that the army of Pentagon auditors hamstrings contractors and jacks up their prices.

And so it goes: The Pentagon needs a trained corps of procurement experts; no, weapons should be bought by the soldiers and sailors using them. The Pentagon buys too much high-tech equipment that G.I.s can't operate or fix; no, industry behemoths can't move with enough agility to imbue weapons with the latest technology. The Pentagon brass is too cozy with industry; no, inexperienced military buyers don't understand how industry works.

Underlying these disputes is America's basic uncertainty over how to deal with its arms industry.

Because the industry is relatively young -- born during World War II when government arsenals could no longer produce increasingly complex warplanes -- it has yet to find an equilibrium with an American public suspicious of profiteering and the industry's influence on the U.S. economy.

Unlike most industrialized nations -- which have basically socialized their arsenals -- the United States maintains a touching faith in free enterprise as the cornerstone for building weapons. In practice, this is partly true and partly fiction. Where it is true -- where market forces operate -- competition keeps prices down, promotes innovation, and guarantees better quality.

Yet for many weapons there is no competition, partly because the Pentagon seems most comfortable with monopolies and partly because the nation can afford only one producer of some of its biggest and most vital war machines. Only one shipbuilder is now capable of supplying aircraft carriers; the Pentagon can suspend General Dynamics Corp. for allegedly cheating on the Divad contract, but then there won't be anyone to build Trident submarines. As the nation buys fewer quantities of more expensive, complex weapons, we will find ourselves at the mercy of monopoly suppliers with greater frequency.

Unfortunately, the lean, hands-off bureaucracy that can best manage competition isn't the ideal apparatus to regulate a utility-like monopoly, which demands the attention of tough auditors and smart buyers. As a result, no one solution, no grand reform, will work in every case.

Still, a few sensible principles seem to have proven themselves over the years. If the Pentagon had begun applying them with zeal five years ago, when it had so many carrots to dangle before a hungry industry, the trillion-dollar buildup might have purchased more defense and fewer recriminations:

*The Pentagon's buying process is so logy that half of the Defense Department's bureaucrats could be fired without any apparent risk to national security. As one procurement expert told Congress earlier this year, "This might prove to be so helpful that in a couple years you could fire one half of those that were left."

*The fundamental ethic underlying most Pentagon contracting -- the more you spend the more profit you earn -- is perversely antithetical to sound business sense. When the Pentagon offers more prudent incentives -- such as tying profits to quality and efficiency -- the arms makers show they can adapt to capitalism, too.

*The nation is not well served by an incestuous partnership between Pentagon and industry, in which captains of industry become assistant defense secretaries and colonels retire today to join the companies they were regulating yesterday.

*With relentless consistency industry and the bureaucracy resist competition, although with equal consistency competition -- when allowed to flourish -- pays fat dividends. The Navy discovered this verity long ago by inviting a second firm to challenge the monopoly on Shrike antiradar missiles, and watching the price tumble from $19,500 apiece to less than $4,000.

Translating principle into practice, however, has defeated liberals and conservatives, Democrats and Republicans, industrialists and generals, all of whom have taken cracks at running what one observer called "the world's largest planned economy after the Kremlin."

Since 1949, Washington has annointed blue ribbon commissions to ponder the Pentagon's management 35 times. Earlier this year, Reagan created yet another panel, recalling as chairman a gruff industrialist who had taken one shot at the monster in 1970 as deputy defense secretary. David R. Packard's assessment then: "Frankly, gentlemen, in defense procurement we have a real mess on our hands."

His preliminary assessment upon returning to head Reagan's commission: "Worse than it was 15 years ago."