Almost everything in the US military relies upon electronics. The economy thrives on electronic trading floors, nationwide networking and a 100% reliance upon business computers. Even the national infrastructure is tied heavily into microchips with computerized utilities and transportation systems. For the longest time, the fear of widespread shutdown came from nuclear EMP but now fear has rightfully turned to simpler, more mundane attacks - hidden kill switches. The DoD is concerned enough with the threat of unknown kill switches residing in much of its equipment that DARPA has been tasked heavily with coming up with a detection technique. The idea is very simple, a kill switch does not need to be embedded deeply into a system to make it shutdown, even if a common integrated circuit responded to an single number transmitted by radio and shut itself down, an entire system could turn off depending on the nature of the shutdown circuit - e.g. power supply. Part of the kill switch conspiracy hubbub was revived following the Israeli air strike against the alleged Syrian nuclear facility. Amazingly, the advanced Syrian radar warning systems "just failed."