Preventing false 9/11 alarms

There's been a lot of discussion in the last six years over what to do if God forbid another 9/11 happens. Shooting down a civilian airliner to prevent it from killing even more people on the ground might be an easy decision if you know the plane's been hijacked but becomes a Hobbesian dilemma when you're uncertain. Israel has developed a relatively simple solution to the problem and is providing