The U.S. aid allowed the Salvadoran military to defeat the Farabundo Martí National Liberation Front ( FMLN ) . In one particular case which occurred in December 1981 , the US-trained Salvadoran army 's elite counter-insurgency unit , the Atlacatl Battalion , commanded by Lt. Col. Domingo Monterrosa , willingly committed retaliation killings at El Mozote , Morazan province , with the result of more than 800 civilians , including 131 children under the age of 12 , murdered during search-and-destroy offensive . The plans to unleash terror against civilians became known to at least one U.S. Special Forces military adviser , which was revealed by Greg Walker , a former U.S. Army Special Forces Staff Sergeant , who served in El Salvador from 1982 to 1985 . Apparently , no formal U.S. government investigation of that particular adviser 's failure to deter the massacre has ever been carried out . Moreover , Returning to the El Mozote massacre , it was duly reported to the American public by Ray Bonner from '' The New York Times '' and Anna Guillermoprieto from '' The Washington Post '' , however , the U.S. State Department denied the participation of the Salvadoran army in mass murder
killings at El Mozote
El Mozote massacre
Foreign internal defense