Actually it's the propaganda about the armed population that's the only deterrent. It would be the "300 million plus" firearms in public hands that might be a deterrent and even that's really questionable because it might simply be ignored. What not an actual deterrent are the actual types of firearms and the people that posses them. Additionally the deterrent value is very limited when compared to the military deterrent for one simple reason. The only serious concern for the invading army is how to disarm the population and not how to fight it. . .