In early November 1975, the South African government warned Savimbi and Roberto that the South African Defence Force (SADF) would soon end operations in Angola despite the failure of the coalition to capture Luanda and therefore secure international recognition for their government. Savimbi, desperate to avoid the withdrawal of South Africa, asked General Constand Viljoen to arrange a meeting for him with Prime Minister of South Africa John Vorster, who had been Savimbi's ally since October 1974. On the night of 10 November, the day before the formal declaration of independence, Savimbi secretly flew to Pretoria to meet Vorster. In a reversal of policy, Vorster not only agreed to keep his troops in Angola through November, but also promised to withdraw the SADF only after the OAU meeting on 9 December. While Cuban officers led the mission and provided the bulk of the troop force, 60 Soviet officers in the Congo joined the Cubans on 12 November. The Soviet leadership expressly forbade the Cubans from intervening in Angola's civil war, focusing the mission on containing South Africa. The Cubans suffered major reversals, including one at Catofe, where South African forces surprised them and caused numerous casualties. However, the Cubans ultimately halted the South African advance.