References:
NSA has their own chip manufacturer: http://en.wikipedia.org/wiki/National_Security_Agency#Role_in_scientific_research_and_development
Hardware backdoors are practical (defcon 2012 slideshow): http://www.slideshare.net/endrazine/defcon-hardware-backdooring-is-practical
Backdoor in military chips from China: http://www.scribd.com/doc/95282643/Backdoors-Embedded-in-DoD-Microchips-From-China
Rakshasa: http://www.extremetech.com/computing/133773-rakshasa-the-hardware-backdoor-that-china-could-embed-in-every-computer