The New York Times reports that US and/or US-allied forces in Syria may be using white phosphorous munitions in the assault on Raqqa, capital city of the Islamic State in Syria. The use of white phosphorous in war is a perennial complaint among human rights activists. And while it's valid as far as it goes, it misses a larger and more important point.
White phosphorous — nicknamed "Willie Pete" by the US mortar, artillery and air forces who use it — produces highly visible plumes of white smoke, justifying its use to mark targets or screen movements.
It's also highly incendiary. It sets things on fire, it causes terrible burns, and it can't be put out with water (it must be smothered and deprived of oxygen). For that reason, international law prohibits its use "on personnel" and in populated areas.
When I worked with 81mm mortars in the US Marine Corps, those restrictions were treated jokingly. Sure, we couldn't use Willie Pete on personnel, but we could use it on equipment. Rifles, rucksacks and helmets are equipment, right? If someone happens to be wearing or carrying that equipment, that's THEIR problem, right? One of our favorite training missions involved firing white phosphorous rounds, theoretically to "mark the target," followed by high explosive rounds. That kind of mission was nicknamed "shake and bake."
I'm glad that I was never called upon to fire white phosphorous at other human beings in combat (I was, for all intents and purposes, a rifleman during the Gulf War). But when tremble in retrospect at that possibility, it occurs to me that the focus on a particular munition doesn't do justice to the problem of war crimes as such.