Somewhere around I have a tape by a guy named Barry Sadler called "Ballads of the Green Berets", which comes from around the period of the US's military success and socio-political failure in SE Asia. I haven't listened to it in years, but my recollection is that it exemplifies the comments made previously that one person's folk is another's country-western. Perhaps we tend to reserve the "folk" basket for anti-anything songs, and refer to pro-whatever songs as "patriotic" or "popular".