SINCE the new administration's attitude toward South Africa is moving fast into controversy, it is worth checking President Reagan's own views. Asked recently if the United States should make South Africa a full-fledged partner in the struggle against communist expansion and drop its concerns about human rights, he said, "No, no." He then suggested that "there's been a failure, maybe for political reasons in this country, to recognize how many people, black and white, in South Africa are trying to remove apartheid . . . As long as there's a sincere and honest effort being made, based on our own experience in our own land, it would seem to me that we should be trying to be helpful." Can the United States, he wondered, "abandon" a wartime ally, a friendly country and a supplier of strategic minerals to boot?

It was a careful and modest answer and, in other circumstances, might have been received as such. Saying "no, no" to strategic partnership, Mr. Reagan accepted apartheid as the limiting factor and set a reasonable if arguable standard -- a "sincere effort" at removal -- for American judgement of it. If that were all there would be little argument.

But of course these words are not all. By a series of deeds, the administration has encouraged widespread fears in Africa and in the United States that it intends to do precisely what the president says he will not do -- embrace South Africa, apartheid notwithstanding.

There is the administration effort to open the legal door to joining South Africa in offering military help to forces opposed to the Cuban-supported government in Angola. Meanwhile, South Africa is given time and room to seat the government of its choice in Namibia. The new American approach to terrorism has emboldened Pretoria to believe that anything it does by way of retaliation or preemption against guerrillas and their sponsors is okay by Washington. Their official fight against apartheid in South Africa has been in suspension -- one hopes only in pre-election suspension -- for some time, but nonetheless, this week some Reagan officials floated the idea of inviting Prime Minister P. W. Botha to Washington after his expected victory next month. Incredibly, some officials also considered inviting the leader of one of the black puppet "homelands".

Mr. Reagan is under no obligation to have black Africans write his South Africa policy for him. He does not have to contribute from his side, as Jimmy Carter sometimes seemed to from his, to the debilitating notion that the United States must choose between black and white in Africa. A respect for efforts at peaceful change within South Africa could have a positive fallout here as well as there.

At the same time, Mr. Reagan cannot leg strategic considerations blind him to African political realities. The recent Soviet navy visit to Mozambique, for instance, should have been taken in Washington no simply as alarming evidence of African unreliability but as the predictable sequel to a devastating new South African raid on a guerrilla center in Maputo. The raid followed guerrilla attacks in South Africa. Those atacks arise directly from the racism of apartheid.

Apartheid is the mainspring of politics throughout southern Africa. Apartheid provides the Soviet Union its only openings in the region. Apartheid alone makes a conceivable reality out of the "resource war" that the secretary of state and other American strategists sometimes postulate. Apartheid keeps South Africa from being the American strategic partner it other wise would surely become.

Meanwhile, Mr. Reagan needs to recognize that strategic, political and economic benefits of a close association with black Africa. These benefits are different from but not less advantageous or available than the benefits of association with white South Africa. The United States should seek them both.