AFTER Nixon resigned, the N Viets violated the treaty and launched a massive tank attack into South Vietnam. The democrats in Congress had passed a bill preventing us from even giving our allies supplies! President Ford went on nationwide TV and asked Congress to supply our allies. They refused.
I think the liberals believe (or at least claim) that the US military actually lost in Vietnam because the war was a "lost cause." It never happened, you can thank the Kerryites for the loss of that peace.
Good comparison.