Answer:
The North Vietnamese army attacked the U.S. Marine garrison at Khe Sanh. It was through the air the supplies were sent at the base of Khe Sanh.
Step-by-step explanation:
The Battle of Khe Sanh started in 1968 when troops from North Vietnam (PAVN) with massive artillery attacked the U.S. Marine garrison at Khe Sanh. Khe Sanh has been a US base since 1962, and its location played an important role in observing the Minh Trail.
During the attack the Khe Sanh base was besieged and cut off, leaving the only way to resupply by air.