Aside from Al Qaeda, what terrorist groups are threats to the United States?

Aside from Al Qaeda, what terrorist groups are threats to the United States?

Erroll Southers (Former Deputy Director of the California Department of Homeland Security) gives expert video advice on: What is Al Qaeda and why is it so successful?; How did Al Qaeda start?; Where does Al Qaeda get its money? and more...

What is interesting is that a number of terrorist groups that you see in the Middle East, like Hezbollah and Hamas, are active here in the United States. In some cases, they are out in public. One of the groups I have not seen here is Tamil Tigers, who invented suicide bombing. In fact they had females carrying out suicide bombings long before the Palestinians did them in Israel. I would saya lot of what you would call your Jihadi Salafi groups in Hezbollah, Hamas, Al Qaeda, Jamas, Lamah -- those are the groups that have us on their radar screen. They are very active throughout the world. There are a lot of different reasons which no one ever really wants to be quoted because we really don't know why they are not hitting the United States, but we are certainly not their friends, if you will.