The group assassinated Admiral Luis Carrero Blanco in December 1973. At the time, Blanco was seen by many as the most likely successor to Spain’s dictator, Francisco Franco. He was killed when an underground bomb exploded underneath his car. More than twenty years later, ETA nearly assassinated Jose Maria Aznar, an opposition politician who later became prime minister. In 1987, ETA killed 21 people in Barcelona using a car bomb.