THE CAMP DAVID agreements have broken the Arab world into those states that can be expected to support Egypt's reach for phased movement toward an overall peace, those that need further convincing, and those substantially opposed. In the first category are Sudan, Morrocco and, one hopes, others to come. In the second are Jordan and Saudi Arabia - Secretary of State Cyrus Vance has been working on them. In the third are Syria, Algeria and assorted others. The last group is committed to a Palestinian dream inconsistent with the more modest Palestinian solution contemplated at Camp David, if not with the continued existence of Israel as a sovereign state.

Along with elements of the Palestinian Liberation Organization, the radical Arabs will no doubt do what they can by terror and political means to spoil the summit. They will try to keep moderate Palestinians and Jordan from joining a West Bank process. For their effort, they deserve contempt - and some pity. If other states play a responsible part, they need not succeed.

What worries us more right now, to be blunt about it is the threat posed to the Camp David accords by Menachem Begin. It may seem ungracious, in this moment of celebration, to identify him in a prospective spoiler's role. Yet what is one to make of the way he has been acting a good part of the time since the summit "frameworks" were signed? He has stressed not the three partners' common enterprises but the putative victories he gained on this or that point and the losses inflicted on the others. He has cast a shadow on the sincerity of his public tributes to Anwar Sadat by seeming ready to take political advantage of him, especially in regard to the West Bank.

And why? The excitement of the moment seems a poor explanation. Surely a leader whose political standing is as high as Mr. Begin's cannot claim that he need abide by no restraints in his effort to appease the ultra-nationalists of the Israel right. It would make no sense for Mr. Begin to so humiliate Mr. Sadat that Egypt would withdraw from the "framework" meant to lead to a quick and full Egyptian-Israeli peace treaty.

Prime Minister Begin has succeeded in raising the destructive suspicion that te might like to render it politically impossible for Jordan and the Palestinians to join the negotiating process offered in the West Bank "framework." That maneuver presumably would be intended to leave Israel with a treaty on one flank and the status quo on the other: the separate peace that many Israelis have long hoped to achieve. It would put Mr. Begin in strange harness with the radicals Arabs - as though they, to hold open the possibility of a Palestinian state, and he, to cement the Israeli hold on territories occupied in 1967, shared an interest in spoiling the summit's West Bank plan.

We think it urgent for the Begin government to make plain that it is as serious about the West Bank framework as it is about the Sinai framework. One concrete way it could do this would be to accept the American contention, one supported by President Carter's personal notation on the relevant document, that at Camp David Israel agreed to halt new West Bank settlements not only during the short period of negotiations on a peace treaty with Egypt, but also during the longer period of negotiations on a "self-governing authority" on the West Bank. Ar the moment Mr. Begin contends that he accepted an obligation only for a shorter period.

It will be a great strain for Mr. Begin, politically and ideologically, to accept the American view. But by doing so he would demonstrate the commitment to Camp David, in all of its parts, that he has begun to bring into question since the summit closed. That is Israel's best way to ensure that peace, first with Egypt and later with other Arabs, will in fact be achieved.