To the people shouting "warcrime". We can't really call these warcrimes. Destroying supplies is a valied war tactic. Weaken the enemy to kill him quick later.
This would only be a warcrime if it were done civilians or done without necessity. In a fight against a prepared, determined enemy would be justified. Or what, is being too hungry or thirsty to kill a tragic circumstance to impose on another.
As for the chemical warfare argument, what do you call tear gas? Her potion was something like laxative + a nauseating agent, hardly lethal. People suffocate faster in tear gas.
And come on, most of us would have done absolute worse given the chance and the motive. The lengths we go to protect the people, community and nations we love. That's how all warcrimes start. Misplaced love.