All joking aside with the Rambo stuff, this was a huge hot button issue in the mid to late 1970's. I believe there were probably a handful of POW's left behind in small interment camps throughout Vietnam, and they were probably held for the purposes of using them for political reasons - i.e. public executions to keep the people in line or to trade for favors from U.S. diplomats, but they were all probably gone by the mid-70's. There would be no reason for the Viet Cong to keep them that long after the war had ended. There are so many M.I.A's from that war that some were probably POW's at some point but either died of disease, starvation, or wounds or were probably executed and buried in unmarked graves. The unnecessary loss of life is always the greatest travesty of war, but the second biggest travesty are the thousands of families who get no closure when a loved one goes missing on foreign soil and are never heard from again.