Guerrilla warfare has always been effective. Did you already forget Hogan's Heroes?
BTW, don't for a second think that we a re losing on any front because of guerrilla warfare. That's not the case.
We are losing because of live video feeds, the internet and the pussification of America.
Back in the day, we bombed entire cities to ruins to force our will. You think the atomic bombs in Japan just targeted soldiers? Did aircraft in Dresden just target soldiers?
Men, women, children, it didn't matter. Don't want to get killed? Don't fight. Protest against your government that's getting you killed.
Now days everything is immediately on CNN/Internet, we are pussified and don't have the stomach to do the real, dirty task of war. So instead we dink around, have unrealistic rules of engagement and sacrifice our soldiers on then altar of pussification.