Pacific News Service ■ , ín his campaign to head off race war in Southem África, Henry Kissinger has.left liis biggest weapons -U.S. economie sanctions - at home. Kissingers strategy is now based on getting South African Prime Minister John Vorster's cooperation on three all-important fronts: economie pressure to forcé Rhodesia's white minority govermnent ib transfer power to black moderates; en'ding South African rule of Namibia (South West África) in favor of a moderate black govemnient ; and reducing the injustices of apartheid in South África itself. But so far Kissinger has been unwilling to use his most powerful optiohs to force Vorster's hand in these areas. According to State Department sources, Kissinger will not threaten to: Enforce UN economie sanctions proscribing trade with South África - cutting off the SI .2 billión in annual U.S. exports to that nation and seriously cripplingits economy. Stop further U.S. private investment in South África - now S2 billion thus ending its major hope for economie expansión. Cutoffall U.S. relations with South África - putting the country into near-total cultural and political isolation. Strictly enforce the UNimposed embargo on all arms sales to South África shaking South África 's confidence in its ability to supply its military machine. While precedents for such sanctions exist in U.S. policy toward other countries - and are, in fact, United Nations policy toward South África - none are under consideration in Kissinger's African shuttle diplomacy, according to State Department sources. Given the urgeney in his ■ current mission to southern África, Kissinger apparently is unwilling to threaten South África with any of the sterner sanctions he could impose. There are several probable reasons: First, Kissinger sees Soulh África as a valuable strategie ' ally. Second, over 400 U.S. firnïs have branches or subsidiarles, in South África, and U.S. oppo: sition ti) white South African policies could jeopardize these investments. Total U.S. investment there - roughly $2 billion - now surpasses U.S. investrnent in all black África combined. The U.S. also experts more than twice what it imports from South África, thus accumulating a large (S600 million annually) and important trade surplus that would be lost if Kissinger were to shut off U.S. trade with that country.