The Weather Underground went on to take responsibility for placing several small bombs in empty offices — the ones at the Pentagon and the United States Capitol were the most notorious — as an illegal and unpopular war consumed the nation. The Weather Underground crossed lines of legality, of propriety and perhaps even of common sense. ... we issued a screaming response. But it was not terrorism; we were not engaged in a campaign to kill and injure people indiscriminately, spreading fear and suffering for political ends.
While there is no standard definition of terrorism, in my mind that is exactly what the Weather Underground was. They committed acts of violence in order to further a political agenda, and they did not stick to merely military targets. To argue that bombings do not cause fear is disingenuous. That they only managed property damage, because nobody wandered into their "response", is fortunate rather than exculpatory.