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.
Foco
Like other theorists of his era (such as Mao Zedong, Ho Chi Minh and Amílcar Cabral), Che Guevara believed that people living in countries still ruled by colonial powers, or living in countries subject to newer forms of economic exploitation, could best defeat colonial powers by taking up arms. Guevara also believed in fostering armed resistance not by concentrating one's forces in urban centers, but rather through the accumulation of strength in mountainous and rural regions where the enemy had less presence.