Of course they should... not that they will actually do anything about it.
They are literally terrorists on American Soil.
The lib hypocrisy appears most evident on this site in regards to violence perpetrated by libs...even to the point of telling lies about TEA party participants.
In pretty much every location the Occupy folk descended upon, the crime went up... they left huge messes for the tax payer (the norm for liberals is to always expect others to fix things they themselves damage) to fix.
Not that the FBI cares. There's a long history of the US federal government spending resources supposedly on "matters of national security" when it's really to suppress political dissent by infiltrating and sabotaging peaceful, nonviolent political activist groups. Don't trust them for a minute, they don't care about terrorist threats. Their goal is to intimidate people who just want to see some change for the better.
The Occupy movement consists of a bunch of nouveau hippies; let 'em smoke their grass and have their drum circles. They are far from a credible threat. Lets not have the FBI waste resources on investigating these people, and lets have them focus their resources on more pressing matters. Opinion stated.
The occupy movement isn't about danger, it is about standing up for a belief that you are truly convicted about. Sure the extremists are there, and they should not be the forward face of the movement, but I think it does more good than bad. A "threat" is a bad word for it, because it is no different than the racial movements of the 60's or the feminist movements. It is a group of convicted souls.
A movement will always fight the social topic of the day and once resolved will move on. The goal of the occupy movement is not for radical change or forceful change, but to change a policy that is attacking the wealth and stability of the American people. It is a social awareness that has short term solutions for a long term problem. Once the wheels of change start the occupy movement will slowly fade to another movement based on the social injustice of the day.
The occupy movement doesn't even know what they are arguing about. Just a bunch of college kids who want to make it seem like their life has purpose while mommy and daddy pay for their tuition. Should the occupy movement begin organizing and rioting, they could be a potential threat. Until them they are just a bunch of hippies.