The extraordinary database, which was put online last week, exposes previously top secret internal CIA reports outlining America's longstanding concerns on China's political, military and economic influence in Tanzania and the inner workings of former president Julius Kambarage Nyerere's government.
The files show how the CIA had an unfavourable view of Nyerere, who was well-respected globally as a great statesman and leader of the pan-African movement.
The decades-old treasure trove of US intelligence reports reveal how the US was apparently uneasy with Nyerere's leadership of the African liberation struggle, describing him as a "fanatic."
The intelligence files suggest that the US government was increasingly frustrated by its inability to control or influence Nyerere, although he was a Western educated African leader.
In one secret special CIA report dated 21 May 1965, US intelligence officers expressed concern at Nyerere's pan-Africanist position, just four years after Tanzania gained its independence from Britain.
"Tanzania under President Julius Nyerere has been drifting slowly but steadily leftward. Today, it has moved into the vanguard of Africa's radical states and offers the Chinese communists an unusually promising opportunity to penetrate the (African) continent," said the top secret CIA file titled "Tanzania Taking the Left Turn."
"This process (of Chinese influence) has been under way at varying speeds since Tanganyika became independent ... but has been accelerated by Nyerere's determination to lead the struggle for the liberation of southern Africa and by Tanganyika's union with Zanzibar. Far from coming under moderate Tanganyikan control, Zanzibar has continued to be a centre from which radical, pro-Communist influences radiate."
In its files, the CIA makes a somewhat skewed opinion of Nyerere in the early years of Tanzania's independence, describing him as a "weak executive who has surrounded himself with radical lieutenants."
"On the question of African liberation, Nyerere is a fanatic. Beneath a charming personality which disarms many Westerners, he is a man of strong conviction, prepared to pay almost any price to achieve a united Africa ruled by black Africans," said the dossier.
"Hypersensitive to any suggestion of outside interference, Nyerere has not hesitated to expel US diplomats and reject West German aid regardless of the consequences."
The sensitive CIA documents noted how China beat the US by becoming the first nation to establish an embassy in Dar es Salaam after Tanganyika's independence and hence "attained the most influential and trusted position."
"China's presence and prestige in Tanzania has increased steadily ... The Chinese may eventually press too hard in Tanzania, but so far they have been more successful than the West or the Soviets in relating themselves to the Africans," said the file.
In July 1971, the CIA conducted a secret intelligence case study in Tanzania titled "Chinese Communist Economic and Military Aid to Tanzania," which shed more light into America's decades-old fears about “all-weather” Tanzania-China relations.
"Communist China has established itself as the principal foreign presence in Tanzania during the past three years. The Chinese are now the primary source of arms and training for Tanzania's military establishment," said the report.
The intelligence files also reveal that the CIA conducted espionage activity to identify possible successors to Nyerere when he leaves office.
In November 1982, the CIA prepared a 25-page intelligence assessment report titled "Tanzania: Nyerere and Beyond" which looked into possible scenarios for Nyerere's possible exit from power, including a military coup.
"President Julius Nyerere's hold on power is slipping, in our judgement, mainly because he and his government are having increasingly difficulty dealing with Tanzania's numerous and deepening economic problems," said the intelligence report.
"US embassy officials in Dar es Salaam report that public criticism of Nyerere has become more widespread as these problems mount. Although we have seen no evidence of any organised opposition, discontent is growing among government officials, military personnel and the general public."
The report also assessed various possible successors to Nyerere in 1982, including former prime minister Edward Sokoine, former army chief Gen. David Musuguri, planning and economic affairs minister Kighoma Malima, Tanzania's ambassador to the United States Paul Bomani, prime minister Cleopa Msuya, Tanzania's ambassador to Canada Benjamin Mkapa and personal assistant to the president, Joseph Butiku.
In October 1986, the CIA produced yet another intelligence dossier titled "Tanzania: Prospects for Change," which was drafted just a year after Nyerere's decision to voluntarily step down.
The US seemed to under-estimate Nyerere's influence on key decisions in Tanzania from behind the scenes after his retirement, saying he would only do so for just a couple of years after his retirement in 1985.
"We believe that former president Julius Nyerere's far-reaching influence will continue to affect the character of Tanzanian politics over the next two years, despite his decision to resign as chief of state ... Nyerere still holds key decision-making power that can undercut the government's authority and give continuing influence to his proteges and followers," it said.