IN 1972 PRESIDENT NIXON secretly gave Iran virtual carte blanche to buy the arms of its choice. Scarcely a year later, OPEC's quintupling of oil prices put into the Shah's hands the money to buy the quantities of sophisticated weapons he has been amassing relentlessly since. Campaigning for President Jimmy Carter decried profligate American arms sales. In the White House, he declared he would view arms sales "as an exceptional foreign policy implement to be used only in instances where it can be clearly demonstrated that the transfer contributes to our national security interests." Putting his policy into effect in respect to Iran, he decided not to sell the F-18.

He has persisted however, in pushing the sale of an elegant airborne radar system called AWACS (airborne warning and control system). Iran wants seven at a cost of $1.2 billion. Evidently the administration feels that American relations with Iran cannot easily stand the strain of canceling AWACS. Moreover, there is strong Pentagon pressure to recapture by exports some of the huge development costs ($2.8 billion). NATO is gagging on the price. Hence the drive to sell to Iran.

It's a pity because on the merits the administration's case is weak. The Director of Central Intelligence agrees that the technology could leak with damaging results to the Russians. The need for Americans to man the system could conceivably suck the United States into unwanted trouble. Since the system lets you control your fighter aircraft as well as detect enemy missiles, it's sale undercuts the formal Carter pledge not to introduce into a region a weapons system creating "a new or significantly higher combat capability." Iraq or Saudi Arabia could reply by escalating their own military preparations. Ground radar provides Iran an alternative. Granted, not all these considerations are of equal merit. But in the 30 days which the law gives Congress to block proposal sales the administration has not satisfactorily answered the questions that overhand this transaction. Said the President on May 19. "The burden of persuasion will be on those who favor a particular arms sale rather than those who oppose it."

Senate Majority Leader Robert Byrd offered the administration a gracious escape from a collision with Congress. Citing the press of Senate business and the non-urgency of the AWACS sale, he suggested that the President wait awhile. But Mr. Carter said no. So a brusing battle is coming. Conservatives as well as liberals are aroused. For the sale to be blocked, both houses must disapprove by Aug. 5. We hope they do. The administration should understand in any event that its stand has fueled a congressional drive to change the law to make it easier to block future sales.