Many of us AHsians are probably aware of the weird/hi-tech weapons of World War Two on back. Things like the Triebflügel, Tsar Tank, and the Revolver Rifle. After WW2, however, I don't recall seeing many of those same hi-tech, wierd, limited or never to be put into action things discussed.
What are some of the weird of hi-tech weapons of the Vietnam war era that never saw production or never made it past limited usage, and how could Vietnam have become a testing ground for the technology of tomorrow (even more than it was in the OTL)?