FIDEL CASTRO, wearing his hat as the current leader of the "nonaligned" movement, did his cause no great good by his speech at the United Nations. He might have underlined the huge stake the developed countries have in the progress of the poor. He might have tried to widen the common ground of interdependence. But he didn't. Explicitly, he chose confrontation. Along with the usual insults about Israel, etc., he offered a harsh and simplistic Marxist analysis that cheered ideologues and antagonized practically everyone else.

There's no point lingering over the policies of Mr. Castro that have increased Cuban reliance on production of a single agricultural commodity of fluctuating price and supply, and increased Cuban dependence on a single foreign power -- aspects of "colonialism" he otherwise decries. Just set aside the complaint that precious resources are being diverted to military uses, coming, as it does, from one who has deployed tens of thousands of troops abroad. He is for now, the chosen leader of the nonaligned states: he is their cross to bear.

When Mr. Castro attributes Third World poverty to colonialist "plunder" and asserts that "imperialists" should compensate by adding $25 billion a year for a decade to the resources being transferred anyway, he is drawing a political cartoon. More than any other factor, the oil cartel is responsible for Third World distress. Cartel members are sucking immense sums -- about $25 billion a year, in fact -- out of the countries least able to pay. The cartel's prices are cutting deeply into the industrialized countries' ability to offer aid to the poor and to take their exports. Yet Mr. Castro tiptoed past the cartel, whose members belong to his nonaligned group. And he gave a free pass to his patrons in the socialist world.

Why bother fencing with Fidel Castro when he's only playing political games? Would that he were only playing. His efforts to stimulate Third World anti-Americanism are of a niece with his global military adventures. They reflect a policy calculated to serve only Cuba's interests, as Mr. Castro perceives them. It pleases him to portray himself and Cuba and, by extension, the group he now nominally leads as engaged in a life-or-death struggle with the United States. But is this dramatic rendering accurate?The Castro truculence has a life of its own, It has kept Mr. Castro from going halfway to bring about the rapprochement Jimmy Carter plainly offered at the beginning of his term.It can keep the Third World from taking full advantage of the limited but still valuable steps the United States is prepared to take on global development now.