HOW CAN YOU CUT the defense budget?

President Reagan, at his March 31 press conference, seemed to be encouraging suggestions from those persons who believe they have some ideas, as long as they did not harm those areas of military effort where his administration is attempting to meet "Soviet superiority."

That was a fair enough challenge, so here goes.

First, one general note. The immediate savings outlined below come to less than $15 billion in fiscal 1982 and fiscal 1983 outlays. Nothing dramatic there.

The cuts proposed here are important, however, because they reduce future-year expenditures by about $160 billion, and those are the high-deficit years that bankers are looking at when they hang onto high interest rate levels. 1.

Save $500 million in fiscal 1982 and $1.1 billion in fiscal 1983 outlays by cancelling the MX land-based ICBM and accelerating the submarine-launched Trident II, which would become a common missile used both on land and at sea. Post-1983 savings: more than $25 billion.

Despite its rhetoric, the Reagan administration has yet to come up with a coherent strategic policy for the 1980s and beyond, or the weapons to go with it. The much-heralded strategic decision last October was in fact the announcement of force reductions (a cut in the Carter MX program from 200 to 100), and continued research aimed at developing a better and cheaper strategic weapons program than the one that was in place when Reagan took office.

In October, it was rumored within the Pentagon that Defense Secretary Caspar W. Weinberger really had become convinced that the best way to go was with a common strategic missile that could be based on land, in deep silos; in the air, aboard long-flying new planes; or at sea, in new Trident submarines. Because the MX was too big for that role, Weinberger was reported ready to drop the almost developed, big, land-based ICBM, and instead go all out for a common missile based on the Navy's proposed Trident II.

But both Weinberger and Reagan had committed themselves publicly to the MX, if not to the land-basing system. Cynics say Weinberger therefore proposed putting the first 40 MX missiles in hardened, then unhardened, silos, knowing that Congress wouldn't go along. It hasn't. The Senate Armed Services Committee, which last year barred fiscal 1982 funds to pay for construction of hardened silos, this month followed through by eliminating fiscal 1983 funds to buy the first nine MX missiles, since there is no place to put them.

That action creates the opening to give Weinberger what he apparently wants but is afraid to ask for. It's time to take the ICBM program to its logical conclusion. Drop the MX now, since it's clear there is no land basing that is acceptable to this administration, and accelerate development of the Trident II missile.

Refocus research on basing modes away from MX and toward Trident II to handle its smaller size, and save substantial sums. Even if you end up with only the new missiles in each of the now-planned 12 Trident submarines, it would be a devastating nuclear force of 1,728 warheads, each capable of destroying any known Soviet missile silo or other hardened target. And the 1,000 Minuteman ICBMs, with 400 older ones replaced beginning in 1988 or 1989 by a land-based version of the Trident II, are good for another 10 to 20 years, barring some arms reduction agreement.

For fiscal 1983, the savings that would come from dropping the MX altogether would be $4.5 billion in budget authority and $1.9 billion in outlays.

In turn you could put $800 million of those fiscal 1983 Air Force MX funds into the Navy's Trident II program, accelerating it by one year, which coincidentally is a matter the White House and Weinberger already have asked the Navy to study. In fact, that $800 million figure is what one defense expert says the Navy has come up with as the cost of buying one year of acceleration. Moving up the Trident II operational date by one year, to 1988, for the first Navy missile would be costly, but it would mean only a one-year slip from 1987, when the first MX is now expected to become available. 2.

Save $150 million in fiscal 1982, $500 million in fiscal 1983 and almost $50 billion in future years by dropping the strategic nuclear role from the mission of the long-range bomber, limiting it instead in the future to delivery of conventional munitions.

This significant dollar saving in strategic forces could be accomplished by the controversial step of finally turning away from bombers as nuclear delivery systems in any war between the United States and Soviet Union. With each side possessing thousands of warheads on missiles carried by submarines or land-based ICBMs that can hit the enemy's territory within 10 to 30 minutes, the need for any bomber that would arrive six to eight hours later seems superfluous.

The Air Force already makes some acknowledgement of this reality. In making its case for the B52 bomber and even the planned B1, it has lately stressed the intercontinental conventional bombing role needed to back up rapid deployment forces. During last year's joint exercise with Egypt, called "Bright Star," B52 bombers based in North Dakota flew nonstop to Egypt, dropped their conventional bombs on a test range in the desert, and returned to their U.S. bases within 34 hours.

If the strategic nuclear role for bombers were dropped, current plans to modernize the latest B52s to handle new, nuclear cruise missiles would be halted. This could turn out to be an impressive saving, since the total B52 modifications are budgeted to cost more than $5 billion when finally completed. Less costly modifications consistent with the B52 conventional role would continue.

Production of the first 50 B1Bs could go ahead under the same formula. The Air Force itself has made changes in the B1 to make it more acceptable as a conventional bomber -- its supersonic speed has been reduced and the bomb bay modified to handle conventional loads. But only 50 B1Bs, rather than the planned 100, would be needed. In the long run, this cutback could result in a saving of $10 billion.

The major dollar cuts, however, would come with a quick windup to the "Stealth" bomber program. That costly plane is being designed solely with the strategic nuclear role in mind. Its most exotic features are supposed to make it possible to penetrate Soviet airspace without radar detection. Its smaller size would make it expensive as a conventional bomber. For the future, the Air Force could take some of its "Stealth" research money and spread it over several years in developing a long-range "Stealth" conventional bomber for the 21st century.

The saving on a strategic "Stealth," whose funding level is classified, has to be estimated. I'd put it at about $400 million in fiscal 1983. 3.

Save $500 million in fiscal 1983 by cutting back on items associated with the strategic bomber program, such as the air-launched cruise missile, and purchase of additional aircraft for air defense such as the AWACS and F15. Another $12 billion would be saved in future years.

For example, some $241 million could be saved from fiscal 1983 outlays by halting production of the nuclear air-launched cruise missile at 1,000 with funds that are contained in the current fiscal 1982 budget. Replacing nuclear warheads with conventional ones for future use could be explored, since conventional warheads are currently being put on shorter-range submarine-launched and ship-launched cruise missiles.

If the United States turned away from bombers and cruise missiles as strategic weapons, particularly as part of an arms reduction program, it would be almost certain that the Soviets would do the same, particularly since they have no present bomber force of any size. Although they have shown a new bomber built along the lines of the B1, the Russians have been extry has coemely slow in developing it.

A reduced Soviet bomber threat would permit another $65 million to be cut in next year's funds by dropping new E3C AWACS that the Reagan administration wants to buy and put in random patrols over the northern boundary as air defense of the United States from Soviet bombers and cruise missiles. Another $200 million in fiscal 1983 could be saved by limiting purchases of new F15 fighter- interceptors designed for the role of air defense against the small threat from Soviet bombers and cruise missiles.

Dropping the nuclear air-launched cruise missile wouldn't be that much of a loss in real deterrence and could be helpful in arms control. Thousands of cruise warheads could be traded away in a future arms agreement, matched by reductions of more effective missile warheads on the Soviet side. And what would be lost? Like the bombers, air-launched cruises pose no real threat to the Soviet Union since they, too, would arrive at the target hours rather than minutes from launching.

The Carter cruise missile plan, put forward when the B1 was originally cancelled, was to build about 2,300 of these nuclear missiles and hang them from B52s. The first Reagan plan that replaced it was to build more than 3,000, and use them with both B52s and B1s. Now it is being said that the cruise numbers are to be raised even higher in the fiscal 1984 budget currently being put together by the Air Force. The new figure, according to one source, is 4,300, with purchases increased to take into account a new "C" version with a lower physical cross-section that makes it even harder to find on radar.

Why does the Air Force want more air-launched cruise missiles? Its favored scenario envisions that in the face of a Soviet missile attack, U.S. bombers would fly several hours to approach the Soviet border before releasing their missiles, which would then continue at subsonic speeds toward whatever target was left that required a nuclear bomb.

The problem with this scenario is that the cruise missile, unlike a bomber which can be redirected, has to be pretargeted. Its guidance system follows a map already built into its computer, which cannot be changed once the plane is in the air. The highly accurate cruise is promoted as a weapon to be targeted at Soviet missile silos. But since it would not be used until after a Soviet first strike, there is a real question as to how many of its targets would still be there.

Privately, Pentagon officials will admit that a major reason for the cruise is to force the Soviets to spend additional funds on air defense systems. Fine, but if history is any guide, we soon apparently will see the Soviets themselves building air-launched cruises, and then we will be the ones who will have to start making major expenditures on air defense for a system that has little likelihood of use in the most unlikely event of strategic nuclear war.

More than 1,000 air-launched cruises have been financed through the fiscal 1982 budget. It's too late to say we won't deploy any, since the first symbolic B52 armed with 12 cruises has already gone on alert, and the first squadron is due next December. But enough is enough. Cancel the next 2,000 and try to make air-launched cruises one of the first nuclear weapons to go in any reduction plan agreement with the Soviets.

For fiscal 1983, the saving would be $863 million in authorizations, $241 million in outlays.

There would be another ripple effect in any decision to halt air-launched cruises and to eliminate the bomber as a strategic weapon. The annual operations costs of the Strategic Air Command could be cut back almost $2 billion a year. If agreement with the Soviets could be reached on dropping cruise missiles, the Air Force could cut back on the new expenditures planned for continental U.S. air defense to meet the Soviet Backfire bomber. 4.

Save the entire $6.8 billion programmed in later years for two new nuclear aircraft carriers by dropping them altogether and using, instead, the 50 new Air Force B1B bombers to perform the same "force projection" role. In the long term this would save more than $20 billion, since there would be no future need to buy additional ships and naval aircraft to accompany and protect the two carriers.

Authorization for two new carriers in the fiscal 1983 budget is looked on by most defense spending critics as the Pentagon's dollar bargaining chip. Analysts say the new carriers would mainly be helpful in maintaining a more reasonable peacetime rotation of these giant ships now that the Navy keeps five of them deployed. In addition to the normal two in the Western Pacific and two in the Mediterranean, the Navy has added one in the Indian Ocean.

Rotating five deployed carriers with a 12-carrier force puts some strain on both men and ships. But the answer probably is to reduce the deployed force rather than add more carriers.

One solution would be to put one of the new battleships, armed with conventional cruise missiles, instead of a carrier in the Indian Ocean, and use B52s if needed to bomb mobile targets. The battleship program, by the way, should be limited to three, rather than the planned four. That would allow a reasonable rotation and save at least another $500 million in the future. 5.

Save several hundred million dollars in fiscal 1982 andfiscal 1983 by halting two questionable, costly Army antitank programs -- the Apache attack heliocopter and the Bradley infantry fighting vehicles. Long-term savings could run as high as $15 billion.

The Army, which is attempting to produce roughly 14 new, complex weapons systems at one time, has run into management and financial problems. As one Capitol Hill observer put it recently, "They have taken on too much."

Congress ought to apply some judicious cuts to these programs, ending some of them before they all go from development into production and soak up the Army's funds now and in the future.

Rather than picking out systems individually, one course of action is to look at those that appear redundant in a single role -- in this case, tank killing. Given that the Soviet Union and Warsaw Pact nations have a numerical advantage in tanks, both the Army and Air Force have embarked on ambitious antitank development programs.

Using the old adage that you can't buy everything, here is an attempt to rationalize what ought to be bought.

A place to start is with the AH64 attack helicopter, which now is expected to cost nearly $16 million per copy. That's too high a price to pay for a limited tank killer, given other Air Force systems being developed, such as the A10 aircraft, and other less costly, albeit less impressive but already proven Army helicopter programs such as the Cobra.

Production of the first 11 AH64s, which were financed by fiscal 1982 money, has not yet begun because the price offered the Army was too high. Take advantage of the negotiations and end the program. Pay off Hughes Helicopters and the other contractors and put the remaining money in the smaller Cobra helicopter and the Air Force ground-support antitank effort.

There is roughly $500 million in fiscal 1982 funds that can be used to pay off the old contractors. The fiscal 1983 saving would be $1 billion in budget authority, $106 million in outlays.

Another program that ought to be ended is the more- than-10-year-old effort to build the M2 and M3 infantry fighting vehicles. These battlefield taxis, costing more than $1 million each, carry less than a squad of troops and have been looking for a role in the Army. One hint that they were in trouble came when it was decided to beef them up by putting two antitank missiles on them. Again, there is $900 million in fiscal 1982 money that can be recaptured, or at least used in part to pay off the contractor, FMC Corp., which is slow getting production started. Use the remaining funds for more of the traditional M113A2 armored personnel carriers. For fiscal 1983, the saving would be $965 million in budget authority, $86 million in outlays.

Then there is the smaller, less publicized Viper prs to ogram. The Viper is a hand-held, bazooka-type, anti-tank weapon developed for the Army by General Dynamics under an original contract that put the proposed price at $78 per copy. Killing tanks with such weapons has never really worked out, and even with these so-called modern systems, attacks pretty much have to be made from the side or rear, which means the GI firing the weapon is already behind the enemy's lines.

The Viper's cost has ballooned to over $1,000 apiece, but the Army has gone on to order its procurement. Cut the program before it gets started and buy a newer version of the weapon now in Army use, a Norwegian-built rocket that costs around $200.

The saving this year would be less than $20 million, but since the total planned purchase is in the 700,000 range, future savings could approach $1 billion.

Then, for just plain marginal weapons, there is the M9 armored earth mover nicknamed ACE. It has been in development for over 10 years. But in fiscal 1982, the Army finally got it funded by saying it was needed to keep up with the costly but speedy M1 tank. Now it turns out that the M1 is going to have one or two tanks per company with a blade that can do most of the work the ACE was heralded as doing, and the heavier earthmoving can be handled as it has always been by the slower but far less costly Army bulldozer, not the 1,400 ACEs the Army eventually wants to buy.

Take back the $46 million in the fiscal 1982 budget that was to purchase the first 25 ACEs. It's another contract that has not yet been signed because of a complaint to the General Accounting Office by International Harvester over the way it was awarded without competitive bid to Pacific Car & Foundry Co. 6.

Save almost $3 billion in fiscal 1983 outlays and $39 billion in future years by cutting back on purchases of munitions to be used in wartime and the rate at which defense equipment is maintained and overhauled.

One of the least publicized of the major Reagan administration defense spending increases comes in the areas of purchasing what are called "war reserve stocks" and "real property maintenance activities."

War reserve stocks are, in their simplest form, the shells, bombs, bullets and other items used to fight. How much of this material, which is stored both abroad and in the United States, is enough? How is that decision even made?

The services are directed to prepare their needs based on the hypothetical length of time a war is to be fought and the amount that will bring victory. The Army and Navy have computers on which, according to congressional testimony, they fight out a total war and determine down to the last grenade and shell how many of each item would be necessary.

Under the Carter administration, these war reserve stocks were designed to fight a 45-day war. Under Reagan, the level of stocks to be purchased have been raised to a requirement for 90 days, which equals additional purchases over the next five years of $90 billion in modern ammunition -- twice as much as programmed under the 45-day level of the past.

MIT professor William Kauffman, who has served as an adviser to the past five defense secretaries, has written in the new Brookings Institution book, "Setting National Priorities," that "past underfunding of war reserve stocks is no excuse for future overfunding." His recommendation is to remain at the 45-day level and save $500 million in fiscal 1983, and an additional $16 billion in the future.

There has even been some criticism of overpurchasing of munitions under the 45-day requirement. Take, for example, the new improved conventional munitions for the 155-millimeter howitzer. Costing about $500 apiece, or more than three times a normal shell, these munitions carry and drop 83 grenades over the target (if they work). Between 1977 and 1980, the Army bought almost a million. In fiscal 1981 and fiscal 1982, the Army received funds for almost 600,000 more. The fiscal 1983 budget before Congress calls for another 428,000. That's roughly 2 million of one typeprs to of 155-mm. shell, and there are several other types to be fired from the limited number of 155- mm. guns.

An even lesser known category of defense spending is the money used to maintain and repair defense property. The Reagan administration wants to almost double the amount spent here, adding an extra $2.4 billion in fiscal 1983 and more than $23 billion in future years. As Kauffman puts it: "Do the services really want to wipe out all backlogs of maintenance and overhaul, or would they prefer their civilian work force to be kept stable, busy and proficient?" His answer is to cut back to the current level. 7.

Finally, for a quick hit in budget saving, force the Pentagon itself to reduce another $4.5 billion by not passing the fiscal 1982 military pay supplemental bill.

That can be done because of an unusual situation arising out of the military pay raise that passed last year and went into effect last October. In the current year, fiscal 1982, the Pentagon budget included roughly $6 billion to cover pay raises for its military and civilian personnel, but that figure is not yet obligated. A supplemental appropriation bill for $6 billion should have been sent up to Congress by now to obligate those funds, but has not.

According to Office of Management and Budget officials, a supplemental for about $4.5 billion will be sent up this month. The remaining $1.5 billion is being absorbed by the Pentagon through manpower reductions.

But what if Congress refuses to pass that $4.5 billion defense pay supplemental? What if, instead, Congress tells the Pentagon it will have to pay those remaining higher wages -- which are required by law -- by reprogramming some other already approved 1982 funds? That would force another $4.5 billion Pentagon-initiated reduction in fiscal 1982 outlays.

The services, it is worth pointing out, know where to find previously appropriated money that's no longer needed. They do it all the time when they want to reprogram funds to pay for things like increased costs on items they want. Then they go to Congress and explain. For example, last July the Air Force needed an additional $13.6 million to buy another C130H cargo plane because the price had gone up. VoilMa! Air Force officials found an unneeded $13.6 million in fiscal 1980 appropriated funds that were still around and unused. Of these, some $8.9 million had been approved originally to buy three types of combat planes but never actually spent. The remaining $4.7 million came from a fiscal 1980 account which the service itself described as "unobligated contingency funds" which sat around for a year awaiting just such a situation.

There is no right way to cut defense spending, just as there is no single way to spend it. Weapons programs, however, should have been put together to meet some defined threat in a national way. Those who want to reduce those programs should do it in a way that provides a means for meeting the threats, or proving they do not exist.