The National Liberation Army was a Marxist-Leninist

Marxism-Leninism

Marxism–Leninism is a communist ideology, officially based upon the theories of Marxism and Vladimir Lenin, that promotes the development and creation of a international communist society through the leadership of a vanguard party over a revolutionary socialist state that represents a dictatorship...

 guerrilla

Guerrilla warfare

Guerrilla warfare is a form of irregular warfare and refers to conflicts in which a small group of combatants including, but not limited to, armed civilians use military tactics, such as ambushes, sabotage, raids, the element of surprise, and extraordinary mobility to harass a larger and...

 organization that operated in Bolivia

Bolivia

Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...

 during the 1960s and 1970s. It was formed by Che Guevara

Che Guevara

Ernesto "Che" Guevara , commonly known as el Che or simply Che, was an Argentine Marxist revolutionary, physician, author, intellectual, guerrilla leader, diplomat and military theorist...

 and backed by Fidel Castro

Fidel Castro

Fidel Alejandro Castro Ruz is a Cuban revolutionary and politician, having held the position of Prime Minister of Cuba from 1959 to 1976, and then President from 1976 to 2008. He also served as the First Secretary of the Communist Party of Cuba from the party's foundation in 1961 until 2011...

's government in Cuba

Cuba

The Republic of Cuba is an island nation in the Caribbean. The nation of Cuba consists of the main island of Cuba, the Isla de la Juventud, and several archipelagos. Havana is the largest city in Cuba and the country's capital. Santiago de Cuba is the second largest city...

 and the Soviet-led alliance in the Cold War

Cold War

The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...

. Its foco

Foco

The foco theory of revolution by way of guerrilla warfare, also known as focalism , was inspired by Marxist revolutionary Ernesto "Che" Guevara, based upon his experiences surrounding the rebel army's victory in the 1959 Cuban Revolution, and formalized as such by Régis Debray.Its central principle...

offensive, beginning in 1966, faltered and Guevara was captured and executed in October, 1967.

In August, 1973 the ELN joined the Revolutionary Coordinating Junta

Revolutionary Coordinating Junta

The Revolutionary Coordinating Junta or JCR was an alliance of leftist South American guerrilla organizations in the mid 1970s...

 to advance fraternal party

Fraternal party

Fraternal party literally means brother party. The term refers to a political party officially affiliated with another, often larger and/or international, political party or governmental party....

 insurgencies elsewhere in the Southern Cone

Southern Cone

Southern Cone is a geographic region composed of the southernmost areas of South America, south of the Tropic of Capricorn. Although geographically this includes part of Southern and Southeast of Brazil, in terms of political geography the Southern cone has traditionally comprised Argentina,...

 as well as its own. The U.S.-supported military regimes of the region responded with Operation Condor

Operation Condor

Operation Condor , was a campaign of political repression involving assassination and intelligence operations officially implemented in 1975 by the right-wing dictatorships of the Southern Cone of South America...

the following year.