The U.S. promised North Vietnam funds to rebuild its bombed infrastructure. In return, North Vietnam was going to release U.S. POWs.
The U.S. never paid for the rebuilding of North Vietnam, and North Vietnam did not release the prisoners. While Delta Force operators were training to rescue the POWs, some Colonel (not in the U.S. military) purposely announced publicly that he was going to rescue the POWs. He tried and failed, twice. By 1980, all the POWs had been executed due to (Vietnamese) fear of being rescued.
This story was in an article about a Delta Force soldier who trained for the rescue.
