The North was the exact opposite of innocent. They ended up with even more blood on their hands than the Americans (and French and British) that should have never been there.
In the big picture, the US military ordered the killing of North Vietnamese soldiers that were part of a plan to see South Vietnam conquered by any means necessary so a Communist regime could be installed across the whole of Vietnam. The North was an extraordinarily brutal regime, hell bent on military conquest, and murdering anyone that tried to stop them from achieving the acquisition of the South under their ideology. How about we not pretend they were innocent, passive, peaceful, freedom loving peoples that just wanted a unified progressive democracy for all of Vietnam.
It was little different from what happened in Korea, except thankfully the US stopped the North from slaughtering South Korea and installing a dictatorship there.