Washington — South African President P. W. Botha may have cast what amounts to the deciding vote for a policy of United States economic sanctions against his nation. The Reagan administration had hoped that Mr. Botha, in his long-awaited policy address Thursday to a gathering of South Africa's ruling National Party, would be conciliatory enough to hold the US movement for sanctions at bay.
But the speech, described even by moderates in the US Congress as disappointing, appears to have undercut the Reagan administration's position. It has apparently cleared the way for final congressional approval of antiapartheid legislation.
``We need to be very firm about the need for reform in South Africa,'' says Sen. Nancy L. Kassebaum, Republican chairman of the African subcommittee of the Senate Foreign Relations Committee.
The Kansas senator says if such reforms are not made soon, pressure in Congress for more stringent sanctions -- including pulling US investments out of South Africa -- is likely to grow.
Coming in the midst of South Africa's worst racial violence in 25 years, President Botha's speech last week was the focus of an unusual amount of world attention. It was widely expected that Botha would announce, if not sweeping reforms, at least some symbolic gesture, such as the release of jailed African National Congress leader Nelson Mandela.
These expectations were reinforced after a meeting in Vienna last week.
A US delegation, led by national-security adviser Robert C. McFarlane reportedly put South African Foreign Minister Roelef Botha (not related to President Botha) on notice that without reforms President Reagan would be unable to resist the congressional move for sanctions.
But hopes for immediate political reform were undercut Thursday when a defiant President Botha reaffirmed his government's commitment to apartheid.
He said changes in South Africa's policy of racial segregation would put the country on ``a road to abdication and suicide.''
Mr. McFarlane acknowledged that reforms Botha proposed were ``less concrete than they were expressed last week [in Vienna].''
Speaking to reporters at the California White House, he applauded Botha's calls for negotiation, a new constitutional structure, and the ``principle of particpation and responsibility of all South Africans for their country's future.''
But speaking in San Francisco on Friday, Assistant Secretary of State for African Affairs Chester C. Crocker -- architect of the Reagan policy of ``constructive engagement'' -- conceded that Botha's speech was not easily interpreted and raised many questions.''
In his first address since the a state of emergency was declared, Mr. Crocker joined McFarlane in reaffirming the Reagan administration's policy of quiet diplomacy with South Africa.
Crocker said hints by Botha of changes in the apartheid system, including the possible elimination of residence restrictions on blacks, were indications of a ``new commitment to reform.''
But in scattered congressional reactions around the country (Congress is in recess through Labor Day), the speech was generally dismissed as too little, too late.
It was also criticized as too vague to signal any clear change of direction in South Africa's racial policy.
Reactions were strong even from congressional moderates, many of whom have opposed economic sanctions in the past, but who now say they may have little choice but to go along them.
``What was terribly interesting was how fuzzy [Botha] made the crucial sections on reform,'' says Senator Kassebaum.
Botha will have to clarify his intentions very soon, or lose what hope he had of forestalling sanctions, she says.
Botha's speech hinted at specfic reforms, says Rep. Mark D. Siljander (R) of Mich., an early opponent of sanctions.
``But what's discouraging about the speech is when's that going to happen, Mr. Botha? Rhetoric is one thing, acting is another,'' he says.
Before adjourning for the August recess, the House and Senate agreed on legislation that bans the sale of computer and nuclear technology to the South African government. The bill also calls for more stringent sanctions in one year if no progress is made toward reforming the apartheid system.
The House gave its approval to the bill August 3.
If the Senate goes along, as seems likely, the antiapartheid bill will go to the President's desk in September.
Congressional sources say the President is now faced with a very difficult decision.
In his briefing last week, McFarlane reiterated President Reagan's opposition to sanctions, saying we must ``use our influence to achieve constructive engagement.''
To be consistent, the President would almost certainly have to veto the antiapartheid legislation.
But faced with the likelihood of a congressional override, many say Reagan may be prudent and acquiesce to the inevitable.
``What does the Botha speech give as ammunition to the President to argue for a veto?'' Representative Siljander asks.