What’s the airfield here for?

“From that mountainside, the enemy could almost roll rocks down onto us. I wondered why the base had been established in such a vulnerable spot.
“Very important outpost,” Hieu assured me.
“What’s its mission?” I asked.
“Very important outpost,” Hieu repeated.
“But why is it here?”
“Outpost is here to protect airfield,” he said, pointing in the direction of our departing Marine helo.
“What’s the airfield here for?” I asked.
“Airfield here to resupply outpost.”

Excerpt From: Colin L. Powell. “My American Journey.”