The ELN's goals are characterized as anti-capitalist, anti-imperialist, and heavily inspired by the Cuban Revolution of 1959. Drawing on Leninist revolutionary ideology, the ELN relies primarily on kidnapping and extortion to finance these political goals. The ELN also derives some funding from the narcotics industry, though not to the same degree as the FARC, the country's largest guerrilla group.

The ELN specializes in economic sabotage against the energy companies located in the north and central regions. Most notably, guerrillas target the employees and executives of the energy industry, oil pipelines, and electricity infrastructure. The ELN also threatens politicians, union leaders, cattlemen, and other ranchers in the oil-rich northern region.

The ELN is governed by a five-member central command, consisting of Nicolás Rodríguez, Antonio García, Pablo Beltrán, Ramiro Vargas, and Oscar Santos.

The ELN's hardline Domingo Laín front allegedly bombed the Caño-Limón pipeline, Colombia's second-largest crude oil export pipeline, at least 166 times in 2001, causing a substantial drop in national income.

The ELN evolved from a small group of urban radicals in the 1960s into a powerful political-military movement in the 1990s.

In the early 1960s, a group of radical students in Bogota formed the "Movimiento de Obreros, Estudiantes, y Campesinos" (MOEC, or Movement for Workers, Students, and Peasants), to help orchestrate urban labor strikes, boycotts, and anti-state demonstrations. Inspired by Fidel Castro and Che Guevara's call to overthrow the corrupt governments of Latin America, MOEC was Colombia's first self-declared "fidelista" political group. The ELN's founding members came from the MOEC.

The 1948 assassination of Jorge Gaitán, the Liberal party presidential candidate, also influenced the ELN, as it had the FARC. Gaitan's daughter and her peers from the radical faction of the National Popular Gaitanista Movement organized a trip to Cuba in the early 1960s to obtain financial and military support from the Castro regime. The faction, renamed the United Front for Revolutionary Action (FUAR), began to receive regular financial support from Cuba to establish a Colombian foco, or guerrilla group.

In 1965, Fabio Vásquez Castaño, the well-educated son of a Liberal family whose father was killed by Conservative party militias, began to organize other militant FUAR and MOEC members into the first ELN unit in the central region Santander.

After winning its first battle in the town of Simacota in Santander, Vásquez and his cohorts drafted the "Simacota Manifesto," which declared the foundation of the ELN and its armed revolutionary mission.

More peasants and rural bandits were attracted to the ELN's all-inclusive political agenda and that the guerrillas could offer them protection from right-wing paramilitaries. Furthermore, radical priests joined the ELN due to the group's mission to improve the lives of small farmers and poor peasant communities.

One of its founding members, Father Camilo Torres, a progressive priest from an upper-class family, drew urban radicals and progressive Catholic priests into the small ELN group with his call for "popular unity" against an elitist government that neglected the poor.

Manuel Pérez and Domingo Laín, two defrocked Spanish priests, would continue to influence the guerrilla's political-spiritual premise after Camilo Torres died in 1966.

Pérez led the ELN's political and philosophical movement from the 1970s until his death in 1998; he effectively banned the guerrillas' participation in the illicit drug industry on moral grounds.

During the 1970s, the Colombian Armed Forces cracked down on its leftist insurgent movements. Two senior ELN leaders were killed and its resources were drained by the Colombian army's intense offensives.

The ELN largely depended on assistance from other leftist groups in Central America and Cuban leader Fidel Castro, and the Soviet Union.

When the Soviet and Cuban aid stopped flowing in the late 1980s, the ELN increasingly relied on kidnapping and extortion. Despite the depleting money supply, Perez did not sanction drug cultivation based on the ELN's Catholic tradition. Though Perez would not permit the cultivation of coca and poppy crops, some ELN fronts in northern Colombia do derive profits from "coca taxes" and narcotics trafficking.

The ELN allied briefly with the FARC and other guerrilla movements through the "Simón Bolívar Guerrilla Coordination" in the early 1990s, but remained isolated from other leftist groups.

In fact, the ELN's membership has dropped from its peak of 5,000 in the early 1990s to its present 3,500 largely due to its strict adherence to more unpopular guerrilla methods, such as its rejection of the drug trade, allowing the freedom of religion, and its rejection of Maoist communist ideology.

After Perez's death in 1998, Nicolás Rodríguez, a.k.a. "Gabino", became the ELN's commander-in-chief. Rodríguez helped found the ELN in the mid-1960s as a tough fourteen-year old fighter. Some analysts say that Rodríguez has eased some of the ELN's rules, such as allowing greater participation in the drug trade.

As part of a national peace initiative, the government began truce talks with the ELN and the FARC in 1998. Despite the collapse of negotiations with the FARC in 2002, the ELN and government representatives continued talks in Havana, Cuba for several months. The government initially offered to grant the ELN a 1,860 square-mile demilitarized zone in northern Colombia, the reported location of the ELN's central command.

However, the Colombian government officially terminated talks with the ELN in early June, saying the guerrillas were not committed to the objectives of their peace agreement.

-- By Liz Harper, Online NewsHour