True, Zaire is one of Africa's largest and most populous and relatively most moderate states and it's been more friendly than not to American political and economic interests for nearly two decades. True, it deepened its claim on Washington by lending itself to the previous administration's secret involvement, aborted when revealed, in the Angolan civil war. True (or so it appears) it's in some trouble at the moment now that Angola, tasting revenge, seems to be sponsoring attacks on the old Katanga part of Zaire (the former Congo) by separatist-minded Katangese. And, true, it's better that the new administration should send emergency military aid openly rather than again go down the CIA path. Two planeloads of military gear were dispatched yesterday.

It's still a highly dubious proposition for the United States to deepen its involvement in the murk of Zaire in the way that it has. President Mobutu is not exactly what you'd call Jimmy Carter's type of foreign leader. He runs a crude police state of which the State Department, looking for a silver lining, has just said in its human rights report, "Generally, however, after interrogation non-political prisoners are not subject to repeated beatings." The United States professes not to know what kind of soup Zaire is really in, Whether Cubans are training the Angolan mercenaries, or financing them, or merely offering moral support; or whether the emergency American military aid thus far sent or contemplated will do its intended job. There is an open-ended quality to Zaire's predicament -- its long-developing economic predicament as well as its newly developing political one --and it raises the question of whether Zaire is for the United States still a good bet. We have had unhappy experiences with open-ended involvements of which Vietnam, of course, is Exhibit A.

The larger issue is how the United States intends to treat the disputes among black states which are endemic on the African continent. This is the first one to explode since Jimmy Carter became President --indeed, it is the first foreign military conflict of any kind in which he has involved the United States -- and people are naturally looking at his policy for what precedents it may hold. We find his approach troubling. He has not explained the contingencies or stakes which require such a abrupt American response, nor the risks of delay. He has not indicated that the United States is moving by diplomatic means, say, by appealing to the Organization of African Unity or even to the United Nations, to seek a peaceful resolution of the dispute. He came to the White House promising to shoulder more responsibility for Africa's and the developing world's economic welfare. It is odd to see him reacting to his first challenge in the pattern of the previous administration: hustling more security assistance to a longtime client state which may or may not be under Cuban guns. Why doesn't Mr. Carter slow down and say what his policy is and where he thinks it will fetch us up.