Left-wing terrorism has its roots in 19th and early 20th century anarchist terrorism and became pronounced during the Cold War.^[9] Modern left-wing terrorism developed in the context of the political unrest of 1968. In Western Europe, notable groups included the West German Red Army Faction (RAF), the Italian Red Brigades, the French Action Directe (AD), and the Belgian Communist Combatant Cells (CCC). Asian groups have included the Japanese Red Army and the Liberation Tigers of Tamil Eelam, although the latter organization later adopted nationalist terrorism. In Latin America, groups that became actively involved in terrorism in the 1970s and 1980s included the Nicaraguan Sandinistas, the Peruvian Shining Path, and the Colombian 19th of April Movement.^[1]

Modern left-wing terrorist groups in the United States developed from remnants of the Weather Underground, the Black Panthers and extremist elements of the Students for a Democratic Society. Between 1973 and 1975, the Symbionese Liberation Army was active, committing bank robberies, two murders, and other acts of violence. Most notably, the group kidnapped heiress Patty Hearst.^[10] During the 1980s, both the May 19th Communist Organization (M19CO) and the smaller United Freedom Front were active. After 1985, following the dismantling of both groups, there were no confirmed acts of left-wing terrorism by similar groups.^[11]

Incidents of left-wing terrorism dropped off at the end of the Cold War, partly due to the loss of support for communism.^[12]

Stefan M. Audrey describes the Sandinistas, Shining Path, 19th of April Movement, and Revolutionary Armed Forces of Colombia (FARC) as the main organizations involved in left-wing terrorism in Latin America during the 1970s and 1980s. These organizations opposed the United States government and drew local support, as well as receiving support from the Soviet Union and Cuba.^[1]

The Revolutionary Armed Forces of Colombia (FARC) is a Marxist–Leninist organization in Colombia which has engaged in vehicle bombings, gas cylinder bombs, killings, landmines, kidnapping, extortion, hijacking, as well as guerilla and conventional military. The United States Department of State includes the FARC-EP on its list of foreign terrorist organizations, as does the European Union. It funds itself primarily through extortion, kidnapping and their participation in the illegal drug trade.^[13][14] Many of their fronts enlist new and underage recruits by force, distribute propaganda and rob banks. Businesses operating in rural areas, including agricultural, oil, and mining interests, were required to pay "vaccines" (monthly payments) which "protected" them from subsequent attacks and kidnappings. An additional, albeit less lucrative, source of revenue was highway blockades in which guerrillas stopped motorists and buses in order to confiscate jewelry and money. An estimated 20 to 30 percent of FARC combatants are under 18 years old, with many as young as 12 years old, for a total of around 5000 children.^[15] Children who try to escape the ranks of the guerrillas are punished with torture and death.^[15][16]

The May 19th Communist Organization, also referred to as the May 19 Communist Coalition, was a United States-based, self-described revolutionary organization formed by splintered-off members of the Weather Underground and the Black Liberation Army.^[17] The M19CO name was derived from the birthdays of Ho Chi Minh and Malcolm X. The May 19 Communist Organization was active from 1978 to 1985. It also included members of the Black Panthers and the Republic of New Africa (RNA).^[18][19] According to a 2001 US government report, the alliance between Black Liberation Army and Weather Underground members had three objectives: free political prisoners from US prisons; appropriate capitalist wealth (through armed robberies) to fund their operations; and initiate a series of bombings and terrorist attacks against the United States.^[18]