While COINTELPRO was officially terminated in April 1971, domestic espionage continued. Between 1972 and 1974, it is documented that the Bureau planted over 500 bugs without a warrant and opened over 2,000 pieces of personal mail. More recent targets of covert action include the American Indian Movement (AIM), Earth First!, and Committees in Solidarity with the People of El Salvador. Documents released under the FOIA show that the FBI tracked the late David Halberstam—a Pulitzer Prize-winning journalist and author—for more than two decades. "Counterterrorism" guidelines implemented during the Reagan administration have been described as allowing a return to COINTELPRO tactics. Some radical groups accuse factional opponents of being FBI informants or assume the FBI is infiltrating the movement. COINTELPRO survivor Filiberto Ojeda Rios was killed by the FBI's hostage rescue team in 2005, his death described by a United Nations special committee as an assassination.