They also fought for the freedom of future Yanks in another way. The Domino theory was widely believed to be likely to occur if Vietnam fell to the "left wing Communist scum" (I love that saying), and if this happened then US corpotations would have lost a lot of slaves in Asia, which would have led to the accelerated rate of growth of fascism in the US. So fighting in Vietnam halted fascism until Dubya took the throne.
Does this sound plausible or am I just pulling it all from my arse?
“There are no boundaries in this struggle to the death. We cannot be indifferent to what happens anywhere in the world, for a victory by any country over imperialism is our victory; just as any country's defeat is a defeat for all of us.” – Che Guevara
“We still believe that the struggle of Ireland for freedom is a part of the world-wide upward movement of the toilers of the earth, and we still believe that the emancipation of the working class carries within it the end of all tyranny – national, political and social.” – James Connolly