Symbolism, Imagery, Allegory
A pilot named Captain Trouin explains to Fowler how he's not terribly upset at attacking towns that have the opportunity to fight back, but he dreads using napalm, a weapon that spreads fire indiscriminately and destructively.
The first time I dropped napalm I thought, this is the village where I was born. … The baker—I was very fond of the baker when I was a child—is running away down there in the flames I've thrown. (3.1.5.18)
It's an image of power without control and the guilt that comes with using it. Fowler never uses napalm, but when he arranges to have Pyle killed, he's playing with fire. Pyle plays with fire in the person of General Thé, but he doesn't feel the guilt when things go awry.