Grapevine

LIGHT AT THE TUNNEL'S END. The negotiators working on a timetable for the withdrawal of 50,000 Cuban troops from Angola have learned not to underestimate Fidel Castro. When South African forces mounted a successful operation in Angola at the end of 1987, Castro rushed in as many as 5,000 additional troops, including his own elite presidential guards. Largely because of Castro's move, South Africa backed off and resumed peace talks. Now Castro insists that his troops leave on Cuban ships and planes, not Soviet ones. "Fidel put everything on the line," says a U.S. diplomat. "He's determined to leave Angola with his head held high."