Yes it is easy to blow up shopping centers. Hence the Boston Marathon bombing. Hence the surveillance programs that ostensibly identify and investigate and stop potential bombers.
The existence of 'security theatre', the only example I can think of being the TSA, doesn't preclude the possibility that there are real threats.
The existence of 'security theatre', the only example I can think of being the TSA, doesn't preclude the possibility that there are real threats.