By reaffirming its intention to sell sophisticated AWACS radar surveillance planes to Saudi Arabia, the Reagan administration faces what is likely to be a six-month ordeal of trying to pick its way through a political and diplomatic minefield without having its policy goals blown up along the way.

The irony is that, to a large extent, it was the administration that planted these booby traps in its own path. While senior administration officials are unanimous in insisting that the AWACS sale is of vital importance to long-range U.S. strategic interests in the Persian Gulf, many concede privately that the matter was handled in a way that is almost a textbook example of how policymakers can create unnecessary problems for themselves.

The aim, which originated in the final days of the Carter administration and which then was picked up by the Reagan team after it took office in January, is to cement U.S. ties with Saudi Arabia and to introduce into that country a stockpile of advanced U.S. weaponry that the Saudis theoretically might make available for joint use with the Americans in the event of a serious military threat to the gulf region and its vital oil supplies.

So far, though, the execution has been carried out in ways that threaten achievement of this goal. The administration's handling of the matter has so antagonized Congress that a majority of its members currently appear inclined to exercise their legislative perogative of vetoing the sale, and administration officials admit that the lobbying effort necessary to stave off the humiliation of a congressional rebuff probably will delay further progress on the deal until September or October at the earliest.

In addition, the administration's actions have strained U.S. relations with Israel in ways that could mean serious new setbacks for the already dim hopes of movement on the Mideast peace process. They also have raised the specter of a new Middle East arms race that could put the United States under pressure to aid Israel, Egypt and Jordan with hefty new outlays that White House budget officials fear will have disruptive effects on President Reagan's fiscal austerity campaign.

In an attempt to reconstruct how this situation came about, The Washington Post has talked with a large number of administration and diplomatic sources familiar with various aspects of the AWACS deal. Although their respective accounts differ in some respects, the points on which they collectively agree add up to a story of bureaucratic rivalries, cross purposes and failures of communication stretching over two presidential administrations and that include these main points:

The U.S. Air Force, in its enthusiasm for getting advanced weapons like the AWACS (Airborne Warning and Command System planes) and F15 jet fighters with enhanced offensive capabilities into Saudi Arabia, got too far out in front of the political process necessary to lay the groundwork of congressional and public opinion support for such controversial sales.

The Carter administration, during its final days, engaged in some duplicitous maneuvers that both helped to commit the successor administration to a course from which it would have been difficult to retreat and to provoke the current high level of Israeli suspicion about the reliability of American commitments.

Secretary of State Alexander M. Haig Jr., who has been tagged with a temperamental image of hard-line militaristic dogmatism, was, in this situation, the player who argued strongly but unsuccessfully for a cautious, go-slow approach that many officials concede, in retrospect, might have averted many of the problems now confronting the Reagan administration.

The new administration's attempt to avoid the policy turf fights of recent years by downgrading the functions and authority of the White House National Security Council staff failed in this situation, because it meant that there was no adequate mechanism for coordinating the divergent views of the State Department and Pentagon and providing the third-party staff work that might have identified problems early in the decision-making process.

The origins of the story go back to 1978 when the Carter administration, responding to Saudi pressures, successfully bypassed the opposition of Israel's supporters in Congress and put through a deal to sell Saudi Arabia 62 F15s, with delivery to begin in 1982.

The key factor in warding off a congressional vote to block the sale was a letter from then defense secretary Harold Brown assuring members of Congress that the jets would be purely defensive in nature and would not have special range-enhancing capabilities and extra armaments that would make them a threat to Israel.

By early last year, however, the chaos in Iran and other events had alarmed Saudi leaders to the extent that they were pressing the United States to sell the offensive enhancement equipment for the F15s that Brown had promised to withhold. That led to a June 1980 meeting in Geneva between Brown and the Saudi defense minister, Prince Sultan, at which Brown is understood to have cautioned Sultan to wait until after the U.S. presidential election and to have left him with the impression that the Saudi requests would get a sympathetic and probably favorable hearing at that time.

In late October, as the election campaign whirled toward its end, President Carter, bidding for American-Jewish votes, publicly ruled out providing multiple-ejection bomb racks for the F15s. Although bomb racks were the only type of equipment specifically mentioned by Carter, his statement, made in a television interview, also included this remark:

"There will be absolutely no change in the assurance given to the Congress in 1978 by Secretary Harold Brown, acting under my instructions, on the sale of F15s to the Saudi Arabians."

In subsequent negotiations with the United States, the Israelis were to seize upon the words "absolutely no change in the assurance" to insist that they had understood Carter to mean that the original pledge by Brown remained intact and that all enhancements were ruled out.

But, although the Israelis are known to feel that the Carter administration never disputed ths interpretation directly when it was broached in private discussions, a different scenario began to unfold secretly within the lame-duck administration shortly after Carter lost the election to Reagan.

In an April 1 response to a request from Sen. Carl Levin (D-Mich.), Brown and former secretary of state Edmund S. Muskie conceded that, following the election, the Carter administration "arrived at a tentative conclusion" that it was "favorable disposed toward an early and positive decision" on selling the Saudis range-increasing fuel tanks and advanced air-to-air missiles for the F15s. The letter added: "We were also favorably disposed toward an eventual future sale of AWACS."

The AWACS planes, which the Saudis had been seeking to buy, became a major factor in the situation last September when Carter, responding to Saudi fears that the war between Iran and Iraq might spill over and threaten the Saudi oil fields, sent four of these planes to Saudi Arabia. The planes and their U.S. crews and support personnel are still there.

According to well-placed sources, the quick dispatch of the planes impressed the Saudis and heightened their expectations about the kind of equipment they could obtain from the United States. In this, the sources agree, they were encouraged by Air Force Gen. David C. Jones, chairman of the Joints Chiefs of Staff, who saw the situation as a wedge to begin expanding the U.S. military presence in Saudi Arabia.

Jones and his Pentagon allies viewed a major arms package as the opportunity for the biggest buildup of prepositioned, front-line U.S. weapons in the Persian Gulf since the fall of the shah of Iran. While the Saudis would own and control these weapons, they could not, for the foreseeable future, operate and maintain them without U.S. help, thereby giving the United States the opening to move in quickly and use them jointly to thwart an attack from any country in the region or the Soviet Union.

In retrospect, some Pentagon officials now believe that the wrong lesson may have been drawn. These officials contend that a really effective American ability to aid the Saudis in a crisis requires long and careful political and military planning and that the Air Force, with what some call its "Aladdin's lamp" approach, perhaps convinced the Saudis that things could be done fast and with few problems.

In any case, the sources agree, last November, Jone's prodding convinced Brown and Carter's national security affairs adviser, Zbigniew Brzezinski, that U.S. interests called for getting a sizable arms package to the Saudis. tEventually, the sources add, Muskie came around to this view, and the only strong opposition at the high levels of the Carter administration came from then vice president Walter F.Mondale.

According to the sources, Mondale insisted that, at the very least, Carter should not proceed without first consulting the Israelis and the incoming Reagan team. The sources added that a decision was made to keep U.S. intentions secret from the Israelis, but, as Muskie and Brown admit in their letter to Levin, the Carter administration did inform Reagan's transition representatives of their conclusion that the Saudi deal should go forward and offered to put the matter to Congress before Carter left office.

That offer was declined by the Reagan people, who said they preferred to review the situation and reach their own decisions after they took over.

As things turned out, the sources continued, the Reagan administration, once in office, concluded quickly that it liked the general outlines of the arguments advanced by the Air Force. It particularly fitted well with Haig's desire to put a new priority emphasis on U.S. ability to intercede militarily in the gulf region.

But, the sources added, differences emerged within the new administration about the best tactical approach to take. Whereas Defense Secretary Caspar W. Weinberger advocated going ahead with the whole package including AWACS, Haig took the position that the need to deal with the anticipated angry Israeli reaction made it wiser to go ahead first on the F15 enhancements and leave the AWACS to be handled separately at a later time.

In fact, he evolved a carefully conceived strategy of boxing the Israelis in on the F15s by convincing them that the United States had a compelling interest in satisfying some of the Saudi demands, that the new Republican-controlled Senate would back Reagan in a showdown and that the United States would compensate Israel by finding a way to provide it with an additional squadron of F15s under favorable financing terms. As a result, the Israelis grudgingly agreed to offer only pro forma opposition on the F15 part of the Saudi deal.

However, the sources said, during this period, the Air Force was continuing its negotiations with the Saudis and, without the knowledge of the State Department, led the Saudis to believe that the AWACS would be sold along with the F15 equipment.

In March, when rumors of the AWACS sale began to surface in the press, the State Department said only that consideration was being given to some kind of air surveillance equipment for the Saudis and insisted that it might be a less sophisticated, more limited system like the E2C Hawkeye.

In actuality, the sources said, the only system ever really considered was the AWACS and the only argument was whether it would be included in the F15 package or taken up later.

What decided the argument, the sources said, was a combination of factors: the fact that the Pentagon had left the Saudis with an impression that would be difficult to go back on without charges of bad faith, the failure of the NSC staff to detect the divergences between the Pentagon and State approaches and come up with possible options and Haig's preoccupation with headline-making struggles with the White House over bureaucratic turf.

As a result, the sources said, Haig was unable to put across convincingly his arguments that including the AWACS would jeopardize his delicate arrangement with the Israelis and lead to a bitter fight in Congress where insufficient work had been done to prepare the ground for such a sale.

According to the sources, the Pentagon enjoyed the advantage of having been able to use its military personnel to keep its arguments and negotiations moving at a time when State was still going through the transition phase of bringing in new people. As a result, the sources said, the Defense Department was able to marshal what looked like the more convincing case, including the confident assertion by Weinberger that no more than 35 senators were likely to oppose the AWACS sale.

The matter was formally decided at an NSC meeting on April 1 -- two days before Haig left on a Mideast trip that included visits to Israel and Saudi Arabia.

But, the sources stressed, by the time of the NSC meeting, the outcome already was clear: most of the senior White House staff had come down on Weinberger's side, and Haig, together with national security adviser Richard V. Allen, made only perfunctory arguments for splitting the package.

According to the sources, Haig even failed to win approval for a proposal to try and soften the blow by bringing the Israelis a concrete plan for financing the additional F15 squadron. Instead, he was authorized only to offer the Israelis some lesser compensations such as a small aid increase and promises of increased Israeli defense exports to the United States.

Originally, the plan decided at the NSC meeting called for beginning to notify Congress of the decision shortly after it returns tomorrow from recess. nBut, even while Hair was in the Middle East, the predictions he had made about big trouble began to come true.

The Israelis exploded in anger and vowed to oppose the entire Saudi package by every means at their disposal; a thunderous roar came out of Congress making clear that the sale has no chance of getting past that hurdle at the current time, and the administration was left in the position of lamely announcing last Tuesday that it still intends to go ahead with the package, but stoutly refusing to say when.

Senior administration officials still insist that with time and effort they will be able to swing congressional sentiment around. But even the most optimistic of them concede that it will be midsummer at the earliest before their efforts begin to show results and that the AWACS situation will, as one put it, "be hanging over our heads like a sword on a thread for quite a while as a reminder that we really didn't do our homework on this one."