On March 1, 1971, a bomb exploded in the Pentagon, causing significant damage but no fatalities. The bombing was carried out by a left-wing radical group, the Weather Underground Organization, protesting U.S. involvement in the Vietnam War. The explosion was a symbolic act of defiance, meant to protest the war and the U.S. governments policies. While no one was killed, the attack raised concerns about domestic terrorism in the U.S. The bombing prompted tighter security measures and increased surveillance of radical groups.