The United Kingdom deemed the Rhodesian declaration an act of rebellion, but did not re-establish control by force. A guerrilla war subsequently ensued when Joshua Nkomo's Zimbabwe African People's Union (ZAPU) and Robert Mugabe's Zimbabwe African National Union (ZANU), supported actively by communist powers and neighbouring African nations, initiated guerrilla operations against Rhodesia's predominantly white government. ZAPU was supported by the Soviet Union, the Warsaw Pact and associated nations such as Cuba, and adopted a Marxist–Leninist ideology; ZANU meanwhile aligned itself with Maoism and the bloc headed by the People's Republic of China. Smith declared Rhodesia a republic in 1970, following the results of a referendum the previous year, but this went unrecognised internationally. Meanwhile, Rhodesia's internal conflict intensified, eventually forcing him to open negotiations with the militant communists.