Apocalypse Now (Spoiler)

This question is based on the end of the film, a theory as some of the end was left a bit untold for me, did Captain call in the napalm strike on his position before climbing off the boat and up into the temple to kill Colonel Kurtz? Or maybe it was Chef? In the end it only shows the Captain walking away with Lance and nothing else, a part of me thinks one of them did call in the napalm strike, i'm curious as to what others think.