IIRC, the surviving leadership of the Viet Minh after the Tet Offensive despised Giap for the fact that they had been all but annihilated. Instead of helping them to rebuild, the NVA basically started taking over all major strategic operations. When they started infiltrating into South Vietnam, instead of supporting the VC, the NVA had their own 'government in a box' cadres that would take over villages.

I read a book written by someone who was a big supporter of the Phoenix Program, and they mentioned that the NVA would basically show up to a village, claim that the Americans were going to attack the village, and they needed to defend it; then they would fortify the village in an obvious manner, provoke an airstrike from the ARVN that would destroy the village, tell the people that the Americans bombed the village, evacuate them to a new location in Cambodia, and turn them basically into a loyalist, NVA, supporting village. The local VC connections could fuck off, or get absorbed. A few were even assassinated (also blamed on the Americans).