WHAT WITH political tensions rising and embassy parties turning into slanging matches, it was beginning to look as though the United States and Israel could do nothing together right. For that reason alone -- there are others -- it was good to see the two countries, plus Egypt, coming to a belated resolution of the dispute that had arisen in the summer over the supervision of Israel's withdrawal from the Egyptian Sinai. The Kremlin's refusal to permit the continuation of the United Nations Emergency Force remaining from the 1973 war had created a vacuum. The dispute over how to fill it arose not so much from the question of replacing UNEF as from the pattern of American-Israeli relations that took shape during the summer. The United States was wondering whether Israel was genuinely committed to fulfilling the Palestinian parts of the Camp David Accords and Israelis suspected that the United States was carrying the accords too far.

The wider suspicions remain. But this week the two governments were able to isolate the issue of Sinai policing, and it was quickly solved. The solution involves simply expanding a bit the surveillance mission Washington accepted after the Egyptian-Israeli disengagement agreement of 1975. With Cyprus-based reconnaissance planes and with a few hundred unarmed men on the ground, the United States will supervise withdrawal lines and arms levels in designated zones. Egypt and Israel have their own roles. No formal role is allotted the United Nations, which Israel regards as politically unreliable, but United Nations truce supervisors may be worked in if the parties agree. These arrangements will last until Israeli withdrawal is completed in 1982.

At the time the American peacekeepers went into the Sinai four years ago, some anxious Americans asked if the United States were not setting itself up for "another Vietnam." In fact, far from becoming the magnet for a deepening intervention, the peacekeepers have merely sharpened their volleyball game. This is not to say that Congress, which will be asked to approve the next stage of American participation in Sinai, should not ask all the pertinent questions about it. But it is worth taking a certain satisfaction that this particular venture in American diplomacy has been going well.