So for all those guys crying war crimes. It's not. I just did some research, and scorched earth tactics are not condemned if the it serves a military purpose.
Here it is used to slow down the enemy and force them to retreat. As the end says, sick soldiers are a greater burden than dead ones.
The geneva convention mentions "willfully causing great suffering or serious injury to body or health", which should not be associated with neccessary military operations.
Otherwise almost every action in war is a war crime.