In its lead editorial on June 23 "A Two-Year Defense Budget?" , The Post argues that adoption of a two-year budget for defense would weaken congressional control over the Pentagon, reduce scrutiny of major weapons systems and increase military spending. On the contrary, I would argue that if defense budget decisions were made less often, both the Pentagon and Congress might have time for more thoughtful consideration of big decisions, especially with respect to weapons systems, and resources might be more efficiently spent. Greater efficiency means buying the same defense capability for less money.

The current system might be described as continuous budgeting. Not only are spending decisions made annually; they are reviewed in three sets of congressional committees -- authorizing (armed services), defense appropriations and budget. Two houses of Congress and three sets of committees mean at least six separate series of hearings, debates, markups and votes on defense spending each year, not counting supplementals.

Continuous budgeting absorbs enormous amounts of time and energy both in Congress and at the top of the defense establishment. Moreover, when decisions are so frequent, they are never final. One vote comes hard on the heels of the last. The number of planes or tanks or missiles to be purchased changes frequently, to the detriment of efficient production schedules. Controversial weapons systems, such as the DIVAD or the MX, are debated ad nauseam, but hardly ever either killed or definitively accepted. They just limp from one vote to the next while their costs escalate.

If budget decisions were made less often, they might be less subject to erratic change. Far from abdicating responsibility for weapons systems, as The Post expects, Congress might take the decisions more seriously, knowing it would have to live with the consequences for two years. The Pentagon would also be forced to do more accurate forward planning or eat unforeseen cost escalation. Setting production schedules further in advance could reduce costs. I see no basis for The Post's fear that biennial budgeting would "insulate the Pentagon from fiscal considerations."

A two-year budget is one useful step toward more effective decisions; committee consolidation is another. Perhaps authorizing and appropriating for defense programs were once clearly differentiated functions, but the distinction has long since become blurred. A single Committee on Defense, exercising what are now authorizing and appropriating functions, could more effectively debate defense policy and oversee Pentagon spending.

Congress has wisely pushed the Department of Defense to take the important first step of producing an experimental two-year budget for FY1988 and 1989. The Post should be applauding this progress, not bemoaning the possible demise of the present ineffective system of continuous budgeting.