THE HARDEST things to cut in the defense budget are weapons. Every cut carries risk, the arguments are technical, there are always jobs involved, and savings in the early years are mostly small. The temptation is to turn to the easier pastures of the Pentagon's operating budget. No one ever lost an election for voting to cut maintenance. But weapons cuts are the only way to bring down the budget in the long run, as Congress is trying to do.

As ever, the Congressional Budget Office is offering sensible guidance. Every year it publishes a book called "Reducing the Deficit: Spending and Revenue Options." Some CBO analysts disparage it, but their work is better than they know, a well-reasoned tour through soft spots in the budget, including in the weapons programs. It is a model of how the defense debate should now proceed. Alongside the big argument over how much the country can afford, there need to be a lot of smaller arguments over which weapons it can afford to do without.

A CBO sampler:

*The Bradley fighting vehicle, designed both to take troops into battle as successor to the old M-113 armored personnel carrier and to "fight": it comes equipped with TOW antitank missiles. CBO says "significant savings" -- some $2.1 billion in budget authority over five years -- "could be realized by purchasing upgraded M113s and Improved Tow Vehicles in place of Bradley M2s." These vehicles could not keep up with the Army's new tank over most terrain, as the Bradley could, but "in light of the increasing antitank threat . . . prudence would dictate that, when possible, armored personnel carriers should not be employed alongside main battle tanks" anyway. Choose, Mr. Congressman.

*AHIP, the Army Helicopter Improvement Program, designed to improve the target-spotting ability of scout helicopters until a new generation can be built. But "in recent Army operational tests . . . AHIP-equipped helicopters showed little improvement in performance over that of the existing OH58 helicopters." Congress could save $1.57 billion over the next five years by canceling AHIP.

*The V-22, a vertical-takeoff plane in which all four services are interested. The Marines "have expressed the largest and earliest need" for 552 of them to move men and equipment onto beachheads in amphibious assaults. The V-22 would be better than the helicopters now in use, but it "should not cause operational problems" if the corps were to continue to rely on these for a while longer -- and the corps "has indicated that, by continuing to replace parts subject to wear, helicopter service lives can be extended indefinitely." Army requirements, meanwhile, "are the least precise of all the services," while the Navy is stretched so thin that it might have to take money from other aircraft programs to buy V-22s. "The Congress is already concerned about the number of Navy aircraft programs . . . funded at low procurement rates," the CBO reminds. Five-year savings if the V-22 were cancelled: $4.85 billion.

There are other examples, the Air Force's new AMRAAM medium-range air-to-air missile and C-17 cargo plane prominent among them. The book doesn't say, don't buy. It just shifts the burden of proof a little.