Will this be the year that Congress takes after the defense budget, seeing it not as holy writ laid down by an unchallengeable priesthood but rather as a political document hammered out by competing bureaucracies, each with long-standing vested interests?

It’s a bubbling brew out there, the Tea Party Republicans keen to slash any and all federal programs, joined in a potential alliance of convenience with liberal Democrats seeking to kill big-ticket weapons slammed as pork-barrel waste or Cold War antiques.

The Obama administration’s proposed defense budget for fiscal year 2012, rolled out Monday afternoon by Secretary of Defense Robert Gates, makes for a gigantic target on this shooting range.

All told, it amounts to $702.8 billion, broken down as follows: $553 billion for the baseline discretionary Defense Department budget, $5 billion for a handful of mandatory programs, $117.8 billion for the costs of the wars in Afghanistan and Iraq, and—a category usually omitted in these sorts of analyses but clearly laid out in the tables of the White House budget office—$27 billion for “defense-related” programs in other federal departments, nearly half of it for nuclear-weapons labs, reactors, and warhead maintenance in the Department of Energy.

The money to fight the wars is probably untouchable. First, as a result of the troop pullout from Iraq, it’s a lot less money than the $160 billion funded last year. Second, as was the case last year, Gates is straightforward in itemizing these war-fighting costs ($80 billion for the troops and supplies, $10 billion for equipment to counter roadside bombs, $12 billion to repair and replace equipment, etc.). This is a refreshing contrast to his predecessor, Donald Rumsfeld, who offered no elaboration and stuffed several non-war-related programs into the account to make the baseline budget seem smaller.

But that $553 billion baseline is vulnerable—all the more so, as it’s a bit larger than last year’s amount, and because it’s stuffed with items that are beginning to make some analysts wonder: What does all this have to do with war and peace in the 21st century?

For instance, this budget includes $24.6 billion for 11 new ships, including $4 billion for two new Virginia-class submarines and $1 billion for the down payment on a new aircraft carrier.

Lawmakers should ask the Navy to lay out (in closed-door hearings, if need be) the precise scenarios in which the United States needs more submarines and aircraft carriers than it already has. They’ll find the scenarios are pretty far-fetched.

The budget also includes $9.4 billion to buy 32 F-35 stealth fighter planes. The F-35 has run into so many technical problems and delays that Gates is also requesting $3.5 billion to build more of the planes that the F-35 was supposed to replace, including 28 F/A-18 Super Hornet fighter-attack jets and 12 EA-18G radar planes. Gates is also asking for $2 billion to upgrade the radar on older F-15 planes.

Someone should ask whether it might be a better idea to scale back, or scuttle, the F-35s and to expand the production lines for the modified F-15s and F/A-18s instead. We already have (or have funded) 189 F-22 stealth fighters and 58 F-35s, enough to counter exotic threats from as-yet-nonexistent advanced air threats posed by potential enemies. The older designs, few of which have ever been shot down even though they’re not “stealthy,” are perfectly adequate for all other scenarios.

Then there’s the ambitious plan to build a new generation of nuclear weapons. This includes $1.4 billion to buy 24 new Trident II submarine-launched ballistic missiles, $1 billion in research and development funds for a new nuclear-missile submarine, and $2 billion in R&D for a new nuclear bomber and modifications of the Minuteman III intercontinental ballistic missiles.

Or, as the DoD budget overview puts it, “We are robustly funding all parts of our nuclear triad.”

Much of this largess stems from the pay-off late last year to get enough hawkish senators to ratify the New START treaty. But it’s time to ask some basic questions: How many nuclear weapons do we need? A case can be made for building a new nuclear-missile-carrying submarine, as at some point the existing ones will get too old to send out anymore. Submarines form the most stabilizing “leg” of the “nuclear triad.” They can’t be detected; thus they can’t be targeted; therefore they post the ultimate deterrent to an enemy’s first-strike fantasies. Try to knock out our land-based ICBMs and bombers, and the subs will still be around to blast you to smithereens.

Is anybody thinking about the idea of phasing out the ICBMs? These are the weapons that, over the decades, have spurred first-strike temptations to begin with. They are at once the most accurate and the most vulnerable nuclear weapons. That is, they are capable of destroying, and being destroyed by, the other side’s ICBMs. In other words, their very existence creates temptations of pre-emptive strike in the event of a crisis. They are the weapons, in fact, that generated the nuclear arms race of the 1960s to 1980s. Now that the Cold War is kaput and the notion of first-strike scenarios more improbable than ever, let’s get rid of them—rather than plan to build more of them—while the climate is clear.

Many high-priced elements of the Obama-Gates defense budget are unassailable, or at least invulnerable to political assault: $154 billion for military personnel (including a 1.6 percent pay hike), $52 billion for military health programs, $4.8 billion for more unmanned aerial vehicles (popularly known as “drones”), $1.3 billion for cyberwarfare defense, $500 million for global “train and equip” military-assistance programs. … The list could go on. (There’s also $10.7 billion for missile defense—quite assailable, though for political reasons few will go there.)

It’s also very much worth noting that Secretary Gates, with President Barack Obama’s full backing, has swung a sharp ax the last two years at programs he considers wasteful or ineffective. He’s canceled a few dozen weapons systems, including several that the military services held dear (most notably the F-22, a new Marine landing vehicle, and whole chunks of the Army’s Future Combat System), and forced the chiefs to weed out more redundant or outmoded programs, commands, and whole bureaucratic subcultures than any defense secretary in a half-century, maybe ever.

However, as many of Gates’ champions (and possibly the man himself) are beginning to realize, he hasn’t gone far enough. The politics and economics of federal budgeting dictate a still wider swing of the ax. With domestic programs suffering a freeze at best, the assumptions underlying an ever-growing defense budget are almost certain to come under harsher inspection.

Gates has taken close looks and bold swings at specific military programs. He hasn’t much questioned the missions underlying those programs. For instance, he’s canceled some of the Navy’s more gold-plated ships and some of the Air Force’s more overdesigned jet fighters. But he hasn’t challenged those services’ contentions that a certain number of ships and jet fighters are necessary for national security.

Until very recently, those who proposed to cut the Pentagon budget fell prey to charges of endangering the troops and being soft on defense. More and more lawmakers and analysts are realizing, or saying, that bigger budgets don’t necessarily boost security—and, as a corollary, maybe smaller budgets won’t hurt it.

The question is whether the extra slices will come as the result of serious analysis or whether they’ll just be ripped out arbitrarily, as part of the theatrical rush to slash deficits. The question, alas, answers itself.

Gates is properly concerned about this. At his Monday press conference, he spent most of his time urging Congress to pass the FY 2011 defense budget—the one that he proposed a year ago. That’s right, Congress hasn’t passed it yet. If they don’t pass it soon, a “continuing resolution” will go into effect, unleashing considerable chaos. Several contracts will be halted, forcing manufacturers to lay off skilled workers (who may not easily be rehired if the money is ever re-appropriated) and gumming up the logistics that supply the troops. (Yes, it’s deliberate congressional inaction that’s, more than anything, “hurting the troops.”)

Congress won’t raise the defense budget, for FY 2011 or 2012, to the levels that Gates wants. And probably they shouldn’t. But it’s irresponsible to slash blindly—cutting, say, 5 percent or 10 percent “across the board,” leaving the shreds and shards for the Pentagon’s managers to smooth over. It may be that Gates and his crew have to go back into the budget and scrub out several billion dollars more.

Also in Slate, John Dickerson suspects a better, secret budget deal may be in the works. Timothy Noah explains why the GOP favors such inconsequential discretionary cuts. David Weigel reports on Republican Paul Ryan’s critique of the White House budget. Annie Lowrey describes how your household budget would look if you spent money like the federal government.Become a fan of Slate on Facebook. Follow Slate and the Slate Foreign Desk on Twitter.