An Earth Liberation Front (ELF) faction has claimed responsibility for torching a US Forest Service research lab in Pennsylvania in August. I have friends at this facility and have spent some time there, and very little of their work is related to timber cutting. Most interestingly, about half-way thru the story there's a line about ELF no longer hesitating to use firearms among their tactics (which include bombs and arson). The Left always seems willing to take up arms to accomplish by force what they cannot through legislative or legal means.
http://www.post-gazette.com/healthscience/20020904forest0904p1.asp
http://www.post-gazette.com/healthscience/20020904forest0904p1.asp