Increasing antagonism with the US meant that Cuba was also looking to foil American plans abroad, and the Angolan crisis was a perfect opportunity for Cuba to use its strong military to embarrass the US. Fidel Castro initially acted unilaterally and without notifying the Soviets on his intentions in Angola. However, Cuban and Soviet collaboration soon led to highly effective assistance to the MPLA, with the Cubans provided tens of thousands of well-trained soldiers and the Soviets technical expertise and military equipment, particularly in the field of heavy artillery and tanks, which were previously absent in the Angolan theater. By the 1980s, a Soviet investment of $5 billion in military hardware helped lead the MPLA to victory in the war. Weapons provided included “T-34 and T-54 tanks, 100mm guns, 120mm multiple rocket launchers, amphibious vehicles, helicopters equipped with 20mm cannon and air-to-ground rockets” as well as MIG-17 and MIG-21 fighter jets. Soviet and Cuban presence continued until the late 80s when global political changes and the end of the Cold War took away many of the incentives of remaining in Angola. Without Cuban and Soviet backing, the MPLA would have never been able to defeat its opponents, who also had the support of foreign superpowers.
	The initial reasons for United States intervention in Angola were primarily economic. American oil companies were well established there since the discovery of oil in the 1950s, and in order to protect these interests, the US supported the Portuguese during the liberation war. By the time the Portugal was preparing to leave the continent in 1974, the threat of communist takeover by the MPLA with Cuban and Soviet support influenced the US to fund alternative groups to prevent a communist victory. A Soviet friendly nation in southern Africa might tip the balance of power in favor of the communists and set off more leftist revolutions in the region. Since 1961, the US had been supporting Holden Roberto with a modest stipend of $10,000 a year. In the light of the new situation, this sum was increased to $300,000 in 1975, and throughout that year $35 million was spent on arming the FNLA through airbases in friendly Zaire. US involvement was relatively clandestine at this stage, mostly involving the CIA and indirect aid to the FNLA through Zaire. An American population weary from Vietnam was not willing to enter another bloody Third World conflict so far from home.
Despite the official backing of the FNLA, many within the US establishment did not agree with the decision to support the FNLA. Two important US officials in Luanda, Robert W. Hultslander, the CIA station chief, and Tom Killoran, the American Consul General, agreed that the MPLA were the most qualified of the groups to govern and sought peaceful relations with Washington. Hultslander further stated that its leaders “were more effective, better educated, better trained, and better motivated”; by contrast the FNLA “was led by corrupt, unprincipled men who represented the very worst of radical black African racism.”