Why did the united states us chemical warfare during the vietnam war?

To expose the enemy

Explanation:

The chemical agents burned the vegetation and that exposed the position of the enemy and their hiding places, the main one was the herbicide known as Orange agent.

there were 6 major base camps.   the base camps were located in alva, fort reno, fort sill, the madill provisional internment camp headquarters, mcalester and camp gruber.