This report shows that military support for paramilitary activity remains national in scope, and includes areas where units receiving or scheduled to receive U.S. military aid operate. The report relies on Colombian government documents and extensive interviews with government investigators, refugees, and victims of political violence. Several prominent investigators interviewed by Human Rights Watch were forced to flee the country because of their work collecting evidence on military-paramilitary collaboration. The Human Rights Watch report also links three prominent Army brigades based in Colombia's largest cities to paramilitary activity and attacks on civilians. Together with previous reports, Human Rights Watch has so far documented ties between half of Colombia's eighteen Army brigades and paramilitaries.In a letter to Secretary of State Madeleine K. Albright, Human Rights Watch urged the U.S. government to strengthen human rights conditions on any security assistance to Colombia's military.The letter expressed grave concern that a $1.3 billion aid package proposed by the Clinton administration does not require clear, measurable steps to break links between the military and paramilitary groups.