Sometime this fall Congress may get around to voting on an administration decision to sell Saudi Arabia five planes with highly sophisticated warning systems known as AWACS. The five will replace four American AWACS planes that the United States now flies out of Saudi Arabia for surveillance in the Persian Gulf. The sale of the five will not take place until 1985, and it is possible they will be manned by American crews under American orders. So why the terrible fuss over the AWACS sale now?

Well, Israel is in the midst of an election campaign. Prime Minister Menachem Begin needs every issue he can grasp to prove that he is a doughty defender of his country. So when the White House announced the AWACS sale last Tuesday, Begin assailed the decision the following day. But since everybody knows there's an election campaign in Israel, why did the White House announce the decision?

Well, Ronald Reagan has been shot, and nasty tongues in Washington are telling tales that he is not nearly as well as claimed. So the White House is unusually keen to prove the president is in charge. When reports of division about AWACS between the State and Defense departments cropped up last weekend, the White House saw a chance to demonstrate the president's authority. But why was there division between Defense and State?

Well, unlike Secretary of State Alexander Haig, Secretary of Defense Caspar Weinberger and his deputy Frank Carlucci believe the United States should woo the Saudis by doing them favors. But how was the Pentagon able to assert itself against the State Department on AWACS at this time?

Well, the Saudis openly pushed the Defense Department. On April 19, oil minister Zaki Yamani declared on "Meet the Press" that the Saudis wanted the AWACS decision to be made at once. He intimated that a decision on AWACS was connected to a long-term Saudi policy to keep oil production high, the better to hold prices steady. But how come the Saudis, who are normally given to a low profile, suddenly took such an assertive position?

Well, the explanation lies in an action by Haig regarding sales of equipment to enhance some F15 fighter planes bought by the Saudis three years ago. Haig agreed to sell them the enhancement equipment, but minus some bomb racks that were deemed menacing to Israel. That decision infuriated the Saudis. But why?

Well, Israeli Foreign Minister Yitzhak Shamir had been consulted by Haig about the decision in the course of a visit to Washington at the end of February. Haig struck the bomb racks from the F15 enhancement program, and also gave Israel some concessions on future military sales. The theory was that the Israelis would not then protest the F15 enhancement program. But how did the secret deal between Haig and Shamir become known to the Saudis?

Well, Undersecretary of State James Buckley briefed two congressional committees on Feb. 26. On Feb. 27, the story of the Haig-Shamir deal appeared in The Washington Star. The Saudis had not yet been notified, so they learned of a decision affecting their security through the press after it had first been made known to the Israelis and Congress. The story in The Star, moreover, indicated that Haig was giving the Saudis less in the way of F15 enhancement than they had previously been offered by the Carter administration. But how come the Reagan administration offered a different deal?

Well, like most new administrations, the Reagan crew believes it can do everything better. So instead of signing on to the Carter position and ending the matter there, the Reaganites moved on their own and bought a lot of trouble. But what kind of trouble?

Well, the congressional debate is sure to be long, bitter and divisive. If the administration prevails, the Saudis, beginning in 1985, will have their own AWACS. But they will thus acquire what is widely perceived to be a capacity for seeing everything that happens in Israel. So unless there is miraculous progress toward peace, the Saudis will cross a critical security threshold. In the event Israel sees the need for a preemptive strike, Saudi Arabia, for the first time, may be a potential target.

In the interim, furthermore, the whole world will understand that the president's relation to the national security community is that of an uncertain lieutenant who delegates authority over his company to the platoon sergeants. Every time anyone questions his authority, he shouts to the troops: "Do what I told the sergeants to tell you to do!"