No one has answered the question: What are the alternatives?
Indeed. Instead, it is just the usual pprune slag-the-Yanks idiocy.
On Sept. 11th, the terrorists killed 3000 people, damaged billions of dollars worth of property, and seriously damaged the world economy. If our security fails again and an airliner is inbound towards the Sears tower in Chicago, what do we do? Sit by and watch the plane hit the building and kill thousands on the ground along with the passengers on the plane? Or do we shoot the plane down, saving the people on the ground?
The only security that works is layered security. Shooting down an airliner is the last, worst alternative.
Why would someone criticize the US Air Force for practicing for such an event? Would you rather they did not practice for it, and thus are unprepared if they face this situation in the future?