Shut down the subways, the airports, bus service, taxis, malls, blockade the interstates because they allow easy access from one point to another. Sure, it will be a little inconvenient, but if one bombing is averted it will be well worth it. Everybody stay home, draw the blinds, bar the doors, keep your guns fully loaded with the safety off and on your person at all times. And don't let your women out of the house. If they do leave the house make sure they wear robes from head to toe, including veils. Yes it might be inconvenient in these 100 degree days, but it will be well worth it to keep them safe. If our adminsitration would play a little Half Life 2 I am sure they will pick up some good hints on checkpoints and police procedure.