My father was an army aviator, flying fixed wing in Vietnam around that same time. He also received the DCF, and claimed that it was the only medal he was proud of, besides his CIB. I never learned the circumstances- the mission was classified, and he never heard that it had been declassified, so he didn’t tell us.
I did figure out later that they were doing radio triangulation to locate the enemy. Dad flatly stated that they knew where the enemy were. He also stated that while there, he sat down and did an evaluation of the situation, and determined that we could have cleared everything up in about three weeks (if the political will had been there).
My hat off to current administration that put Jim Mattis is charge and are letting him do his job.