[3] In January 1981, the Farabundo Martí National Liberation Front (FMLN), a left-wing guerrilla group opposed to the junta, began an offensive against the junta and marched on military targets, most notably the Ilopango Airport.

[4][5] In reaction, the United States increased military and economic assistance to the junta and helped establish the Rapid Deployment Infantry Battalions [es], a network of specialized counter-insurgent army units.

[4] The battalion was named after Atlácatl, a legendary indigenous figure from the Spanish conquest of El Salvador who fought against conquistador Pedro de Alvarado.

[6] The United States sent fifteen counter-insurgent specialists to El Salvador in March 1981 to train the newly formed battalion.

[6] The battalion was disbanded in 1992 under the terms of the Chapultepec Peace Accords that ended the twelve-year civil war.