Most of the domestic guys never do anything. Obviously some of these groups are extremely dangerous, such as Earth Liberation Front and others. But in 2008, the vast majority of these guys just want a club to sit around and share their secret handshakes, make fun of other groups and eat hamburgers.

This reminds me of an excellent chapter in Freakonomics about how Real Estate agents and Ku Klux Klan agents are all about information power. This guy infiltrated the Klan, got all of the secret handshakes and words and wrote them into an episode of Super-man.

From this blog:
Kennedy thought of the ideal outlet for this mission: the Adventures of Superman radio show, broadcast each night at dinnertime to millions of listeners nationwide. [...] Kennedy began feeding his best information to the Superman producers. [...] And Kennedy told the producers the current passwords, agenda, and gossip emanating from his own Klan chapter… [...] The radio producers began to write four weeks’ worth of programs in which Superman would wipe out the Ku Klux Klan. [...] Kennedy couldnt wait for the first Klan meeting after the show hit the air. Sure enough, the Klannern was in distress. [...] At the following week’s Klan meeting, the room was nearly empty; applications for new membership had fallen to zero.

Comparing domestic terrorist to international really comes down to motive for me. If a bunch of people get together to promote white pride, black pride, Islam pride, etc... they are probably harmless. If a bunch of people get together to harm people that harm animals or harm Americans, they should be taken seriously.

This begs the question "What about OK City?" First, I've never heard what group they belonged to. Maybe they were in a group? Second, there is a lot of evidence Iraqi nationals were involved in the bombing with McVeigh, but that's probably for another topic.