Thus far, the growing Reagan defense budget, buoyed by a national consensus, has had relatively smooth sailing through Congress. However, that consensus has begun to crumble under the onslaught of deep cuts in non-defense programs, industry running at less than 70 percent of capacity, unemployment over 10 percent and possible deficits in excess of $200 billion. The prospect of defense cuts is now real.

The key issue--if cuts must come--is how to minimize the damage to the defense program. After all, what's withering away is not Soviet military might but only U.S. willingness to exempt defense from the administration's mighty ax.

There are three ways to cut defense. One is to cut the operations and maintenance funds, and another is to cut the size of the Armed Forces. Both of these offer the enticing prospect of near-term savings; both are very bad ideas because they also offer the prospect of a near-term crippling of the military capability we should instead be strengthening.

The third thing that could be cut is procurement. Because these funds are not fully spent until the new hardware they buy is delivered some years hence, the near- term savings from such cuts are small. For that reason (among others), procurement is often dismissed from budget-cutting exercises as futile. But if there must be cuts now, that's exactly where they should be made.

The three Reagan defense budgets thus far have placed a huge emphasis on procurement--33 percent of the total. The operations and maintenance accounts total only 28 percent. That's almost exactly the reverse of what the last administration had planned for these years: 32 percent for operations and maintenance; 28 percent for procurement. That change in balance amounts to a shift in fiscal year 1984 alone of $17 billion into procurement and $14 billion out of readiness.

That procurement-heavy plan is a prescription for disaster if future defense budgets aren't as big as the administration has planned, and if we have once again underestimated the eventual costs of our new hardware. The problem is that it will be very hard later to cut the procurement funds we're about to commit ourselves to now--one can hardly leave a half-finished aircraft carrier on the building ways. The only option will be to cut readiness and the size of the Armed Forces--a sorry prospect for a plan intended to build for the future.

Thus, if we have to cut, we should cut procurement to bring the program back into a better balance between near-term and long-term goals. But what about the need to cut spending now, which procurement cuts don't do?

A cut from this administration's 10 percent real defense growth to, say, the last administration's 5 percent, would amount to $12 billion--no small potatoes, but hardly the solution to a $200 billion deficit, and lost in a $3,000 billion economy, and dubious economic medicine in a time of such deep recession. What Congress should worry about isn't near-term outlays but outlays in the future, when inflation will be much more of a threat than it is now. And those are the outlays that procurement cuts now would reduce.

Though procurement cuts would not come easily, they are possible. For example, a switch from the remaining F14 Navy fighter procurement to the F18, including, say, three missile loads for each aircraft, could cut that cost in half. A switch of the two Nimitz-class nuclear-powered aircraft carriers (appropriated last year but still many years from completion) to conventional Kennedy-class carriers could save a third of their $7.5 billion cost.

Cutting the B1 bomber and replacing it with an aircraft designed only to carry "Stealth" cruise missiles--not to penetrate Soviet air defenses itself--could cut its $25 billion cost in half. On the other hand, the administration's sudden proposal to stop building strategic cruise missiles until an advanced "Stealth" version arrives is the wrong kind of procurement cut. It delays the most economical way of strengthening our strategic forces and gambles needlessly on uncertain technology.

There are other possibilities, but very few would be painless--one cruise missile-carrying aircraft won't do what a B1 will; an F18 won't defend a carrier as well as an F14 will (though we'd still have the many F14s we've already bought); a Kennedy-class carrier isn't as capable as a Nimitz. And, make no mistake about it, such procurement cuts would eventually cut our military strength.

But if cuts must come, better that they come there than in our forces and their readiness. And--whether the economic case for defense cuts makes any sense or not--if the people of this nation feel that the Pentagon must suffer a bit along with everybody else, it would be far better to accept the cuts gracefully and sensibly than to risk further erosion of what's left of the consensus for defense. For if that goes, the security of the nation could be in the most serious jeopardy.