What do you think when you hear the term "no-fly zone"?
There's the exclusion zones set up to stop prying eyes getting close to top security bases, for example Pine Gap, the top secret US intelligence satellite tracking base in the Northern Territory that everyone has known about for three decades.
There's the no-fly zone set up in northern and southern Iraq in the 1990s by the US and UK governments, ostensibly to stop Saddam from gassing his neighbours.
There's the no-fly zone over the White House, Camp David, the "Western White House" at Crawford Texas, and anywhere else those pesky terrorists might try and mow down His Beloved Dubyaness.