What type of unfair fighting used by the north Vietnamese army during the Vietnam conflict?

During the Vietnam War, the North Vietnamese Army and the Viet Cong employed guerrilla warfare tactics, which included ambushes, booby traps, and the use of terrain to their advantage. They often blended in with the civilian population, making it difficult for conventional forces to distinguish between combatants and non-combatants. This unconventional approach was perceived as unfair by some, as it challenged traditional military engagements and contributed to significant psychological and logistical challenges for U.S. and South Vietnamese forces.