AFAIK, Napalm is illegal against a civilian population. IDK that it is illegal to use against military installations.

Not that I think it is necessarily a smart move on the part of Ukraine, since Russia can play this game too.

Russia uses TOS-1 thermobaric heavy flamethrowers A LOT in this war, so either this is lawful or no one cares.

The geneva conventions apply only for wounded and sick on land(geneva convention I), wounded and sick on sea(geneva convention II), captured soldiers(geneva convention III) and at last civilians.

The Hague Conventions on the other hand limit what weapons can be used. in the 1899 article IV may be violated.

Incendiaries are not banned for military targets. Even white phosphorus is only “restricted” such that you need to take precautions regarding collateral damage. And GC specifically doesn’t regulate arms it mainly deals with prisoners and such.

Russia is blowing up schools in Lviv, which is closer to Poland than Russia. I think that ship has sailed