And if the door is too strong, what about the plate glass windows or the brick exterior. There are solutions to any problem, The problem is that, if we turn our schools, then office buildings, then malls, then hospitals, and on and on, into impenetrable prisons, all at taxpayer and consumer expense, the terrorists and bad people, both foreign and domestic, macro and micro, have won, because they have caused us to spend ourselves into poverty over something that can be handled by simply training more people to shoot back. Is it fail safe? No. But neither is anything else that costs a whole lot more money.