Long before that. The NVA and VC were joined at the hip. They were even allied in the fight against the French. In addition, during TET of 68, the NVA were the force at Khe Sanh. They were also the main force at Hue.
People's Army of Vietnam - Wikipedia
But wait. I thought that that most Liberals and Vietnam War Revisionists were claiming that the VC were indigenous South Vietnamese citizens, that were fighting for Communism. Now you are saying they were an arm of the North Vietnamese Government all along.
Oh, and that was not the Vietcong that fought the French. That was the Vietminh.
And yes, almost all of those at Khe Sanh were NVA. But most of those at Hue were VC. Out of the roughly 1.5 Division worth of NV forces at that battle, only a single Regiment was NVA. The rest was all VC. The NVA was to capture the 1st ARVN Division HQ, as well as Tay Loc Airfield and the old Palace. The VC were to take over the rest of the city, specifically targeting for assassination and military, government officials, and law enforcement they could find.
In fact, that was common procedure for the VC. One thing that I find fascinating was how the execution of Nguyễn Văn Lém is often portrayed as a war crime. Yes, he was summarily execut4d in front of TV and print media. The photo is famous. However, what people always neglect to mention is that he was a VC infiltrator, in civilian clothing. And under the Geneva and Hague conventions, that is counted as a "Spy", and such individuals loose all protections.
And also when he was captured, he was leaving the home of an ARVN Officer's family. After killing him, his wife, their 6 children, and his mother by slitting their throats.
Just remember whenever you see that photograph, that shortly before that the individual shot had slaughtered 3 adults and 6 children with a knife. And as obviously shown, in civilian clothing so not protected under the Laws of Land Warfare.
The General that shot him knew the Colonel executed personally, and his family. SO it is no wonder that he had no interest in doing anything other than giving him a .38 migraine treatment.