It has been here already, starting in the early 90's with the first attempt to bring down the Twin Towers. It continued with the attack on the USS Cole and again on 9/11/01 with great success. It has happened numerous times since then though Obama often calls it "work place violence". It will continue and to what degree is unknown but Islam is a "religion of death"! I suspect that Islamic terrorist are all over the country having walked across the porous southern border. There is little that can be done to prevent these isolated attacks. What will the gun toting Americans do if this type attack gets too frequent?