The North Vietnamese Army (NVA) and the Viet Cong, communist forces aligned with the Democratic Republic of Vietnam, played crucial roles in the Vietnam War. The NVA, consisting of well-trained regular troops, operated primarily in North Vietnam and infiltrated the South through the Ho Chi Minh Trail, engaging in conventional warfare during major offensives. The Viet Cong, on the other hand, were guerrilla fighters and local insurgents embedded within South Vietnamese society, employing hit-and-run tactics and underground networks to challenge U.S. and South Vietnamese forces.