"There is no longer any middle ground left," Bill Moyers says as he surveys South Africa at the end of tonight's one-hour CBS Reports documentary on that country. It has come down to the final battle between (white) racists and (black) revolutionaries and the choices for the rest of us are limited to supporting the violence of one side against the other.

A conclusion that stark and chilling can often be true without being totally accurate. The immediacy of television's import telescopes time and creates an image of the possible future, in our perception of what is happening in another country today.

Though skillful and aggressive interviews that range from Prime Minister John Vorster to exiled black revolutionaries, Moyers and reporter George Crile have accomplished a relatively rare feat for television documentary. This program pushes the South Africa story one dramatic step ahead and is likely to change the way you think about The Beloved Country's future, whether you agree with Moyer's conclusions or not.

The production team has chosen heavy emphasis on the Cuban and Russian menace to South Africa, which produces three-quarters of the non-communist world's gold and diamonds, possesses vast stores of other strategic metals and is clearly the African continent's industrial and military giant.

"The Battle of South Africa" succeeds in breaking through conventional discussion of white-black tensions and the continuing bitter after math of the Soweto uprising of June 1976 to bring us directly into the first phases of the guerrilla war that Moyers suggests has already begun.

The strongest segment is the story of a young black South African trained in Angola for guerrilla warfare. As he calmly describes how and why he killed two whites in Johannesburg and then escaped back into Angola, years of newspaper stories speculating about what happens when young blacks become radicalized enough to turn to terrorism become instantly obsolete.

The interview with George Mazibuko, the young guerrilla, becomes a new reference point for charting change in South Africa. Part of the sequence was filmed at a training camp in Angola by the African National Congress, the guerrilla group Mazibuko joined after the Soweto riots. (Unfortunately CBS neglects to identify the source of that footage, a point that is likely to be taken up in the inevitable angry protest this show will draw from the South African government.)

"It's going to escalate this year, it is going to escalate next year," an ANC guerrilla commander says of the war. "There is no way of stopping the escalation."

Instead of stopping to investigate that proposition, the program implicitly accepts it by cutting to film from Havana and a brief discussion by Moyers of "Castro and Brezhnev cast in the role of the liberators of Africa," while Washington looks on wondering where Castro will strike next.

No African guerrilla organization - described on the program with the semantically loaded label of "liberation organization" - has ever received the exposure in America that the African National Congress gets from this edition of CBS Reports. What the ANC will be able to make out of that remains to be seen. It is already clear, however, that this program inflicts significant damage on the vision the South Africa government tries to project abroad.