Pentagon wants to give controversial white phosphorus shells to Ukraine, White House says no

You're going to be downvoted by people who have no idea what a war crime is or isn't, but you're unequivocally correct here.

You won't catch people hand-wringing about the use of anti-personnel mines which is unequivocally a war crime (however, one that's necessary for Ukraine's survival against a genocidal, imperialist invasion also making heavy use of AP mines). However, when indenciaries come up, people somehow have this association that they're blanket war crimes when that's not even close to true. The International Red Cross' summary of Protocol III on incendiaries is as follows:

Incendiary weapons are those that are primarily designed to set fire to objects or to burn persons through the action of flame or heat, such as napalm and flame throwers (Art. 1).

It is prohibited in all circumstances to use them against civilians. It is also prohibited to make any military objective located within a concentration of civilians the object of attack by air-delivered incendiary weapons.

Finally, it is prohibited to make forests or other kinds of plant cover the object of attack by incendiary weapons unless they are being used to conceal combatants or other military objectives, or are themselves military objectives (Art. 2).