panic on the streets of the District

Woke up to 4 policeman patrolling the lobby of my hotel here in DC. I then found machine gun carrying guards and bomb sniffing dogs on the subway. I wonder is there any evidence to support the theory that if a place gets attacked (in this case London) that other places are more susceptible for a few days? This seems to be our approach. A terrorist attack happens, we start strip searching everyone for 4 days and then go back to business as usual.

I'll keep you posted from the road.