Flamethrower

So he's right?

No, they needed to burn the jungles so the Japanese couldn't use the terrain to further advance their ambush tactics. The Japanese soldiers followed the code of Bushido where they wouldn't surrender at the point of suicidal charges, which made their ambushes extremely effective and had great psychological effects on USA troops, so with less places to hide, less potent ambushes. But if they burned enemies in the process, I'm sure they didn't complain.