The most immediate threat to international security comes from the Persian Gulf. But you'd never know it from the defense debate that has built up around the Senate hearings on the arms-control treaty with Russia.

The debate focuses almost entirely on costs and hardly at all on particular forces in particular places. What that skewed emphasis shows is that despite all the talk there is not a national consensus, nor even an emerging national consensus, on defense.

Almost anybody can be cited to demonstrate the character of the defense debate. Here is Secretary of Defense Harold Brown talking to the Foreign Relations Committee the other day on the administration's response to the Russian military buildup:

"In fiscal year '79 we attained the NATO goal of 3 percent annual increase of expenditure. Our FY '80 budget submission provided for a 3 percent increase . . . Our present five-year defense program will require annual increases of at least 3 percent growth, and could well, after analysis, require more."

That numbers game finds justification in the steady decline of militray spending. The military budget has been running down for so long that increases in almost any area do some good. As Gen. David Jones, the chairman of the Joint Chiefs of Staff, said in a recent breifing, there is a pressing need for such "mundane" items as more ammunition, better maintenance of equipment and installations, more hours of pilot training, increases allowances to offset inflation and the depreciation of the dollar.

Such unglamorous items, however, are appetizers for the anti-defense bloc in Congress and the administration, which regularly devours military budgets. While the arms-control debate has weakened the knee-jerk anti-defense group in the senate, they remain very strong in the House of Represenatives and parts of the administration, including the White House and maybe even the Oval Office itself. As a practical matter, accordingly, the only way to get money for many "mundane" matters through the administration and the Congress is to wrap them up in an abstraction like a percentage of the whole budget.

A similar logic applies inside the Pentagon. The uniformed services have allowed their thinking to be dominated by the victory in World War II. They have shaped, and continue to shape, Amercian forces for a big war, and that bent is reinforced by the defense contractors.

Thus the emphasis has been, and continues to be, on the biggest ticket of all -- the nuclear deterrent. Next in importance is the European theater. But other areas of confrontation lag far behind. Moreover, within every service, the most sophisticated technology -- nuclear carriers, high-performance aircrafts, and the most advanced tanks -- takes precedence.

But while the stakes are high in the nuclear area and in Europe, the chance of actual fighting is small. Much more immediate threats to the peace arise in other areas -- notably the Persian Gulf.

Brown and those around him understand full well the need to project American power to the Persian Gulf. But to assert that proirity in the budget runs athwart stiff resistance from the generals and admirals -- most of them far more serious about procurement than strategy -- and their allies in the defense industry and the Congress. Rather than have most of the military industrial complex gang up against a changed budgetary emphasis, the tendency among high Pentagon officials is to buy them off by maintaining intact the basic structure of forces. given the state of the defense establishment, in other words, the easiest way to get an increase anywhere is to get an increase everywhere.

Yeilding to that all-or-nothing pres-sure, however, is a formula for weak military posture, for the big-war emphasis continues even as the danger from more limited encounters grows. The tendency of the military to abandon strategic thought for quartermaster interests is accentuated. The incentive to keep forces abreast of developments in the real world diminishes.

So it is important to impart to the defense debate in the next few weeks a far more detailed character. Pressure has to be put on the services and on the president t come up with a truly good defense program. Our present situation is one in which the incentive is only to cut costs. We are in the position of the man who enters a restaurant and beckons the waiter. The waiter asks: "Would you like to see the menu?" The man replies: "No. Just bring me the check."