If you want to read more about how and why the current system evolved, I can recommend the excellent Command and Control ... fantastic (if lengthy) read: https://www.amazon.co.uk/Command-Control-Eric-Schlosser/dp/0...

For those interested, the Eric Schlosser book is a superb, in depth look at the entire history of nuclear control. Very very good read.

http://www.amazon.co.uk/Command-Control-Eric-Schlosser/dp/01...