Historian Herbert S. Klein notes that a counterinsurgency policy to combat "internal subversion" became a major theme of United States training for the Bolivian army. In 1963 Argentine-trained Bolivian officers established the Center of Instruction for Special Troops (Centro de Instrucción para Tropas Especiales-- CITE) under the Seventh Division in Cochabamba. In addition, by the end of 1963 Bolivia had more graduates from the United States Army Special Warfare School at Fort Bragg, North Carolina, than any other Latin American country. A total of 659 Bolivian officers received training at the School of the Americas in 1962- 63, and 20 of the 23 senior Bolivian officers attended or visited the school during 1963-64. United States military aid increased from US$100,000 in 1958 to US$3.2 million in 1964. This aid, which included weapons and training outside Bolivia, enabled Paz Estenssoro to strengthen the army more extensively than MNR leaders originally had intended. According to Klein, Paz Estenssoro constantly justified rearming the military to the United States "as a means of preventing communist subversion."

In March 1967, Bolivia became a prime target of Cuban-supported subversion when Ernesto "Che" Guevara and his tiny National Liberation Army (Ejército de Liberación Nacional--ELN) launched a guerrilla campaign. Despite its increased United States training, Bolivia's army still consisted mostly of untrained Indian conscripts and had fewer than 2,000 troops ready for combat. Therefore, while the army kept the 40-man guerrilla group contained in a southwestern area of the country, an 800-man Ranger force began training in counterinsurgency methods. With counterinsurgency instructors from the United States Southern Command (Southcom) headquarters in Panama, the army established a Ranger School in Santa Cruz Department. By late July 1967, three well-trained and well-equipped Bolivian Ranger battalions were ready for action. Supported by these special troops, units of the Eighth Division closed in on Guevara's demoralized, ill-equipped, and poorly supplied band. Guevara's capture and summary execution on October 7 ended the ill-fated, Cuban-sponsored insurgency.

The army's increased capabilities and its decisive defeat of the legendary Cuban guerrilla leader enhanced its prestige. The fact that Barrientos's vice president, Luis Adolfo Siles Salines, a conservative civilian, had to request permission from the military high command to assume his mandate after Barrientos's death in April 1969 indicated how powerful the army had become as an institution.

Data as of December 1989