Boeing designed a "robust" fix that includes separating battery cells, a new charging system, venting and a containment box.

CNN: Behind the scenes: Boeing's Dreamliner battery fix

These include the fact that policing is "inextricably linked" with the criminal justice system, and the cost and complexity of separating out national structures and arrangements and the management of national threats.

BBC: Welsh devolution: UK government rejects radical change

The problem is that, as Roberta Wohlstetter pointed out half a century ago in her study of Pearl Harbor, separating out the really important signals from all the "noise" in the system is only easy to do after the fact, particularly when the U.S. government has now assembled a database of an astonishing number of 700, 000 individuals it suspects of ties to terrorism.

CNN: Agencies often miss warning signs of attacks