Spurning his middle-class upbringing in Argentina, Guevara embraced revolutionary politics. He travelled across a number of Latin American countries, supporting a variety of anti-government organizations and using his medical knowledge to assist rebel militia groups. He became intensely anti-capitalist, asserting that interference by the imperialist USA was the root cause of the poverty and political repression of the peoples of Latin America. This notion was intensified by his experience in Guatemala in 1954, where he witnessed what he regarded as the bringing down of the legitimate revolutionary government by a conspiratorial group of reactionary army officers backed and funded by the CIA. When Guevara and Castro met in Mexico in late 1955, they quickly became comrades. Guevara's ideas and experience helped to give focus to Castro's broad objective of overthrowing Batista. The points that Guevara impressed upon Castro were that:
• to remove a powerful military government, the basic strategy must be to avoid direct conflict where possible and fight only on advantageous terms
• guerrilla warfare would undermine the government's superior strength
• effective guerrilla warfare depended on the rebels making common cause with the ordinary people who would then provide them with supplies, shelter and information
• the USA was basically a malign force that would always back reactionary and repressive governments in any country with which it had dealings.