What threat do 'lone wolf' terrorists pose?

Aired: 10/26/2014 | 0:05:33 | Clip
Last Monday in Quebec, a man purposely crashed his car into two soldiers, killing one of them. On Thursday in Queens, New York, a man who had posted comments sympathetic to jihadists used a hatchet to attack four rookie police officers. What's behind these so-called "lone wolf" attacks and what threat do they pose?