I heard a rumor a long time ago that the Boy Scouts of America served as the 13th line of defense. I tried to research this, but I couldn't find anything anywhere online that confirmed this.
I then went to the website of the Department of Defense to see if they had anything on the Boy Scouts and THIS is what I found. Section 4.4 says: "Scouting organizations are not considered part of the military [...]." This doesn't totally disprove the rumor--after all, normal civilians probably are the 14th line of defense or something.
If anyone could shed some light on the subject, I will be very happy. I would really like to be able to confirm or deny this rumor.