 Complete the following phrase:  The GC-45 work was paid for by the South Africans, but it has been claimed that Bull did the work largely at the urging of the United States Central Intelligence Agency CIA who considered South Africa as a defence against Soviet operations in Angola. Used in South Africa as the G5 howitzer, the new guns were used near the Angolan border in 1986 when South Africa invaded the former Portuguese colony of Angola, in order to assist UNITA. Because the Marxist government of Angola was aided by Cuban troops and Soviet artillery, it was also suggested that the CIA had encouraged the South Africans to 