SAUDI ARABIA'S request to enhance the combat capability of the F15s it is acquiring from the United States makes eminent sense from a Saudi point of view. Two years ago, the Saudis made the military and political breakthrough to access to American warplanes. To reassure Israel, specific and firm limits -- no winks -- were put on the planes' range and attack capability. Since then, however, the Saudis quietly explain, the shah as fallen, the Kremlin has invaded Afghanistan, Iraq has deepened its bid for regional primacy, an Egyptian-Israeli peace has given Israel a potentially freer hand on its eastern front, and a heightened sense of instability has gripped the whole region. It is, one can guess, as much to respond to this overall deterioration in the terms of their security as to remove thestigma of being a second-class arms recipient that the Saudis are making their new request. They can perceive, too, that American dependence on their oil and good will has grown in the last two years, and they may well have concluded that they are in an improved position if it comes down again to a toe-to-toe political battle with Israel in Washington.

The Israelis, like the Saudis, see the Saudi request principally in terms of their own anxieties. Militarily, upgrading adds a capability that cuts into the qualitative edge prized by Israeli war planners. Politically, it is a reminder that Saudi Arabia is cutting into Israel's political edge in Washington. Israelis see that in providing the extra accessories, the Carter administration would be overriding the unequivocal range and armaments assurances it gave them when it sold the F15s to the Saudis in 1978 -- this at a time when American assurances are being held out to Israel as the rock on which Israeli risk-taking in peace can safely be based. They note, too, that the administration would be breaking the linkage it established in lobbying the planes through a reluctant Congress: it argued that the sale would bring the Saudis into C amp David. The Saudis have not supported Camp David, they have punished Egypt for joining it, and they have used their influence to keep others out of it.

It is at least possible that the administration will make the strictly political calculation taht in an election year it must turn down the Saudi request. Yet this would be the wrong basis on which to resolve an issue that in any event will only sharpen, in one form or another, as time goes on without further progress on an Arab-Israeli settlement. If it has a political aspect, it remains essentially a diplomatic problem: to satisfy the separate and, to an extent, conflicting reassurances required by Israel and Saudi Arabia and to do so in a manner that does not send a signal of inconstancy to Israel and others who depend on the American word and that does not send a signal of unrealiability and fecklessness to Saudi Arabia and others who count on the United States to act firmly in its own self-interest.

In brief, it is an issue ripe for further study and for a certain amount of shifting from foot to foot. But it also is an issue ripe for being converted by the administration into a vehicle for the education of the American people in the new complexities of the Middle East and, specifically, in the urgency of an Israeli-Palestinian settlement. Obviously Israel has a role in such a settlement. So does Saudi Arabia.With a settlement, which would naturally carry with it a general regionl relaxation, American policy-makers would not have to grapple with jawbreakers like the Saudi request.