EGYPT AND ISRAEL are getting along so famously that there need be no fear that the American-Israel quarrel over a Sinai peace force will damage the peace process. Still, the quarrel is regrettable, if symptomatic. No matter how fervently the United States and Israel pledge mutual allegiance, an irreducible element of awkwardness and tension muddies their relationship. Part of it is the disconnection between patron and client, part of it the disharmony between a country that takes security pretty much for granted and a people accustomed to living on the edge. It puts on both countries a strain they are not always prepared gracefully to bear.

This round began with the Egyptian-Israel peace treaty signed in March. It was plain that the Soviet Union would cast a Security Council veto rather than permit renewal of the United Nations Emergency Force that Moscow and Washington had set up in Sinai after the 1973 war. One alternative suggested early by the State Department was to retrofit for Sinai duty the U.N. Truce Supervision Organization, a small unarmed force created by the General Assembly to police the 1949 Arab-Israeli armistice. In peaceable Sinai circumstances, the argument ran, UNTSO could serve as a plate-glass window and a symbol of international concern for peace. It had the advantage over UNEF of being a permanently constituted force not needing constant renewal and of being a secretary general's creature not vulnerable to Soviet Security Council veto. The Russians, since it cost them nothing, agreed to go along quietly with UNTSO - a clearance that promised to spare a grateful administration the mid-SALT embarrassment of a conspicuous Soviet-American spat.

Such was the timing, however, that the Israelis, who were not of one mind on the matter, did not compose a formal response until last Sunday, two days before UNEF's mandate was to run out. To them, the idea of a force answering to a secretary general recalled nothing so much as U Thant's removal of truce supervisors in 1967, an act that contributed to war. By their reading of the commitment Jimmy Carter accepted in the peace treaty, the United States was obligated, in the event that UNEF fell through, to put together a multinational force on its own (by the American reading, that commitment does not start until Israel fully evacuates Sinai in 1982). That Moscow agreed to the UNTSO plan suggested to some Israelis an American inclination to put Big Two convenience first.

A permanent Sinai force controlled by the secretary general versus a renewable force subject to Soviet veto: the stuff of a good argument. It should be conducted, soberly, by Israel and the United States, and others. They should realize that the treaty creates not only commitments to each other, but also the mutual obligation to explore carefully the new circumstances peace is creating in the Middle East.