A bit of history from their perspective. This has been going on for more than 40 years. Colombia has a very violent and extremely complex history. You can search the names for more info.
You might want to search La Violencia, a 10 year civil war between liberal and conservative that started after the assasination of Jorge Eliécer Gaitán, leader of the Liberal Party.
http://colhrnet.igc.org/timeline.htm Check the photo--a very young Fidel Castro sans beard on the left in Bogota during the riots of April 1948 after Gaitán's assasination.
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36 Years for Peace and National Sovereignty
On May 27, 1964, the Armed Forces of Colombia, directly advised and oriented by the United States of America, initiated the largest military operation of encirclement and extermination known up to that time. The objective: to eradicate the subversive centre that was putting their "national security" and "western democracy" in danger.
This "subversive centre" was composed of peasants who had settled in the region of Marquetalia, Tolima Department after surviving the calamities of the war between the traditional political parties. Poor liberals had fought against poor conservatives, inspired by the leaders of those parties in their power struggle. These peasants of Marquetalia were dedicated to agricultural labour for their own well being and that of the community they constituted. Of the state, they only demanded roads to transport their products, schools for the education of their children and guarantees against the activities of the "pajaros", the paramilitary gangs of that time.
This occurred during the presidency of Guillermo Leon Valencia. The institutions of state, starting with the executive, were in the hands of the liberal-conservative elite, equally shared as a result of the so-called "National Front". The parliament was composed of liberal and conservatives, under the baton of Alvaro Gomez Hurtado, the person charged with generating the conditions in the national and international environment to justify this outrage imposed by a foreign power. He declared Marquetalia to be an "Independent Republic" and described its inhabitants in McCarthyite style (bandits, extortionists, agents of international communism, etc.), and argued that they were another state within the state.
Faced with the evidence of the coming aggression, and in order to find another way out, the inhabitants made every effort to approach all institutions and organizations susceptible to being motivated, including the parliament, the church and the international community, and have them come to that region and know its situation first hand. The only response was a declaration of solidarity by French intellectuals and Father Camilo Torres' attempt to come to the zone, which was prevented by the army.
The President, representing the liberals and conservatives and following the guidance of the yankees, gave the military command a free hand. Operation Marquetalia began: 16,000 men supported by the most modern techniques, advised by Pentagon officials and supported by the big print media, initiated the "patriotic mission" to wipe out that group of Colombians in three weeks. They used every means at their disposal: aerial bombardment, strafing, parachute assaults, encirclements of extermination, bacteriological warfare, torture, summary executions, the buying of consciences and payment of bribes, as well as the jailing and abuse of those who were in solidarity with the "Resistance of Marquetalia".
http://www.farcep.org/pagina_ingles/