Che Guevara
In Guevara's private writings from this time (since released), he displays his growing criticism of the Soviet political economy, believing that the Soviets had "forgotten Marx". This led Guevara to denounce a range of Soviet practices including what he saw as their attempt to "air-brush the inherent violence of class struggle integral to the transition from capitalism to socialism", their "dangerous" policy of peaceful co-existence with the United States, their failure to push for a "change in consciousness" towards the idea of work, and their attempt to "liberalize" the socialist economy. Guevara wanted the complete elimination of money, interest, commodity production, the market economy, and "mercantile relationships": all conditions that the Soviets argued would only disappear when world communism was achieved. Disagreeing with this incrementalist approach, Guevara criticized the "Soviet Manual of Political Economy", correctly predicting that if USSR did not abolish the law of value (as Guevara desired), it would eventually return to capitalism.
René Barrientos
Barrientos had ample opportunity to prove his anti-Communist credentials in 1967, when a guerrilla force was discovered to be operating in the Bolivian southeast under the leadership of the Argentine-Cuban revolutionary Ernesto "Che" Guevara in the Bolivian jungle. Barrientos was very concerned with Guevara's alleged popularity among the miners in the southwestern part of the country, and clamped down in the area with some very heavy-handed measures (such as the Massacre of San Juan). Guevara felt that such an atrocity by the Bolivian Army and Air Force would be the tipping point in his favour in rallying the miners to his Communist cause, but eventually the miners signed an agreement with the government-owned mining company Siglo XX, which agreement Guevara felt undermined his reason for being there. The war between President Barrientos and Che Guevara's militia did not end there, but eventually the Bolivian Army Rangers captured Guevara and executed him in October 1967.