in the united states, terrorism takes the form of bombings. the fbi records more than a thousand terrorist bombings every year. >> it is just startling how widespread bombings, especially these types of protest bombings, were in the 1970s. they happened by the hundreds. >> the weather underground put bombs in the state department and in a military induction center in oakland, california. >> it was not, to me, a weapon that you use to kill people. it was something you use to disrupt things. somebody called them exploding press releases. >> both the washington and oakland bombs were set to protest against american involvement in indochina. >> the problem with lots of little bombs is the first bomb gets page one news. when you're up to the 30th bomb, it's on page six. >> a bomb exploded today at los angeles international airport. >> some groups said, only by being more ruthless can we achieve our goals.