If you read "A Lonely Kind of War" or "Vietnam above the Treetops" you would not make such stupid comments.
The NVA used Cambodia as a highway to funnel supplies to the south. Look at a map of Vietnam and you will understand. The US could shut down the supply lines in country but were unable to bomb even 1 mile into Cambodia until the rules of engagement were changed.
Thus the NVA had a huge supply infastructure inside the border of Cambodia that was untouchable for most of the war.
You say the US bombed cities in Cambodia when in fact they were bombing visible targets identified by Special Forces on the ground supported by Forward Air Controllers flying low and slow with nothing more than smoke rockets to mark the targets.
The targets were training bases road and supply dumbs but mostly trucks that the NVA tried to hide during the day but ran suppies with at night.
