Vengeance! Commando of Fire (1983)
A weapons expert is sent to Vietnam to demonstrate a new weapon he has just invented, but he is captured during a Viet Cong attack and imprisoned in a POW camp. He is rescued not long afterwards, but when he returns home he finds that his wife has been kidnapped and he is being set up for a string of crimes that he did not commit. He determines to find out what's going on and who is behind it.