Besides, if the stronger side always wins, then what happened with Vietnam?
There was a major administration change in the middle of the Vietnam War, which led to an early withdrawl of American presence.
The Viet Cong were fighting in blatant violation of all existing legislation regarding the "rules" of combat...attaching bombs to children, false surrenders, etc, just to name a few. And because they were a legitimate military force, the US was obligated to abide by said rules, despite getting our tails handed to us because the VC was violating the same.
That said, no one can predict what the future might have held had the US not withdrawn from Vietnam when we did. We may have won, we may have lost. We'll never know, so it's really a moot debate.
Assuming the Viet Cong won, which isn't a stretch considering the above, then it's safe to say that the VC were in fact a stronger force, albeit illegitimately, because they won.