I've always heard that we could've won, but we didn't want to, which I think is stupid. My knowledge of the Vietnam war isn't up to par with my knowledge of other wars, so I ask why did we lose, maybe better put, why didn't we win? From an outsider looking in that war was similar to US island hopping in WWII against Japan. Suicide tactics, guerrilla warfare, harsh jungle setting, etc. I'd wager that in Vietnam we had an even bigger technology gap between the two fighting factions than we did in the Pacific Theater.
Well, first of all, it needs to be said that the warfare during the Vietnam War was very different from that in the Pacific in WWII.
I have written a larger post about this, which I am hoping to actually update one of these days with some more recent scholarship, but it's a good introduction. Keep in mind though that I write exclusively about the military side of defeat. There were other factors, political in particular, that played a part.