UNITA forces attacked Camabatela in Cuanza Norte province on 8 February 1986. ANGOP alleged UNITA massacred civilians in Damba in Uíge Province later that month, on 26 February. The South African government agreed to Crocker's terms in principle on 8 March. Savimbi proposed a truce regarding the Benguela railway on 26 March, saying MPLA trains could pass through as long as an international inspection group monitored trains to prevent their use for counter-insurgency activity. The government did not respond. In April 1987, Fidel Castro sent Cuba's Fiftieth Brigade to southern Angola, increasing the number of Cuban troops from 12,000 to 15,000. The MPLA and American governments began negotiating in June 1987.