The tapes, made public by the Richard M. Nixon Library and Museum, contain 154 hours of conversations from January and February 1973. White House tapes released Tuesday capture Richard Nixon as a pugnacious second-term president who talks of hammering out an end to the Vietnam War even if he has to "cut off the head" of the South Vietnamese leader, remarks that an abortion might be necessary if a pregnancy involved an interracial couple and appears preoccupied with savaging his political foes.