For those also wondering (and I’m quoting a comment on Ars so may stand corrected…):
Isn’t this a violation of the Geneva Conventions?
Only if used to deliberately target infantry. The videoed operations so far seem to have been intended to burn away protective cover (trees/brush), which is a permitted use even if there's a risk of inflicting casualties as a side effect of the application of incendiaries.
There’s a lot of people who seem to have a knee-jerk reaction to this “that’s a war crime!!1!”, but it really is not. Incendiary weapons (like thermite, white phosphorus and napalm) are not illegal to use against legitimate military targets, including enemy combatants. It’s only a war crime when it’s used indiscriminately against civilians or in civilian areas.
You can start a forest fire if said forest is used for cover or concealment by enemy military forces. All feasible precautions must be taken to limit the damage to military targets only.
Honestly war crimes just have a lot of misinformation generally. Even in the military. There were people who thought we couldn't shoot someone with a .50 cal machine gun. While this spawns funny jokes like aiming for their uniform buttons, it just isn't true.
Honestly, I think it’s more that people take this info from movies and just run with it than malicious (Russian) misinformation bots (although they don’t mind giving this an extra push I imagine).