The United States restricted the use of incendiaries like white phosphorus after Vietnam, and in 1983, an international convention banned its use against civilians. In fact, one of the many crimes ascribed to Saddam Hussein was dropping white phosphorus on Kurdish rebels and civilians in 1991.

"Saddam used chemical weapons, we used chemical weapons" in slightly different phrasing. What made Saddam's actions illegal was the fact that he was deliberately targeting civilians in an attempt at genocide. It had nothing to do with WP's chemical properties or status under international law. And nobody used WP use in accusing Saddam of crimes against humanity. For example: the Halabja gas attack. Nowhere is WP listed. But maybe that was an oversight. Let's look at UNMOVIC's description of Iraq's use of WP in their (pdf) "Cluster document" (titled "Unresolved Disarmament Issues/ Iraq's Proscribed Weapons Programs") pg. 141 (143 of the pdf):

Iraq also faced the problem of finding a suitable delivery system for its CW agents: to develop such systems may have taken years. The solution found by Iraq was to purchase bombs designed for white phosphorus (an incendiary and smoke bomb) and then, by simple modification, make them suitable for the delivery of a CW agent.

Doesn't exactly make WP sound like a chemical weapon, does it? But back to the NYT editorial:

But white phosphorus has made an ugly comeback.

Don't call it a comeback! It's been here for years!

Italian television reported that American forces used it in Falluja last year against insurgents. At first, the Pentagon said the chemical had been used only to illuminate the battlefield, but had to backpedal when it turned out that one of the Army's own publications talked about using white phosphorus against insurgent positions, a practice well known enough to have one of those unsettling military nicknames: "shake and bake."

At first, the State Department said it had only been used for illumination.

The Pentagon says white phosphorus was never aimed at civilians, but there are lingering reports of civilian victims.

False dichotomy. It doesn't mean WP was aimed at civilians. If civilians are injured in an attack, that does not make it a war crime, as long as they weren't intentionally targeted.

The military can't say whether the reports are true and does not intend to investigate them, a decision we find difficult to comprehend. Pentagon spokesmen say the Army took "extraordinary measures" to reduce civilian casualties, but they cannot say what those measures were.

Cannot? Or did not? What about warning them a week ahead of time?

They also say that using white phosphorus against military targets is legal. That's true, but the 1983 convention bans its use against "civilians or civilian objects," which would make white phosphorus attacks in urban settings like Falluja highly inappropriate at best. The United States signed that convention, but the portion dealing with incendiary weapons has been awaiting ratification in the Senate.

These are technicalities, in any case.

Whether or not US troops used illegal weapons in Iraq is a "technicality?" This is the current position of WP critics. They will do things like falsely claim the Pentagon described WP as a chemical weapon, then claim it's not the important part, the important part is that it's undermined America's credibility. (Ignoring the fact that they are creating this situation by spreading false claims and rumors about a legal conventional weapon.) Or that the important part is Bush lied to get us into war, etc., ad nauseum. Either US troops used WP in Fallujah in violation of the rules of war or they didn't. I for one don't see that as a "technicality".

Not only that, but the NYT isn't getting the "technicalities" quite right, either. (Isn't it sad the New York Times is being fact-checked by an Internet yahoo named "dorkafork"?) Once more on the legality of WP, at the risk of repeating myself: the convention the NYT is referring to is Protocol III. Now even though the US has not signed it, it's use of WP in Fallujah doesn't violate Protocol III. Though the NYT says "but the 1983 convention bans its use against 'civilians or civilian objects'", the problem is that the NYT apparently did not read the entire Protocol. According to Article 1:

2. Concentration of civilians" means any concentration of civilians, be it permanent or temporary, such as in inhabited parts of cities, or inhabited towns or villages, or as in camps or columns of refugees or evacuees, or groups of nomads. (emphasis added)

The presence of civilians themselves makes them "concentrations of civilians." And much in the same way a mosque becomes a legitimate target when insurgents are using it to fight from, "civilian objects" cease to become "civilian objects" when insurgents use them to fight. (Another explanation of why WP isn't illegal can be found here by Juan Cole, who is not the same person as John Cole.)

The Protocol isn't the only thing the NYT didn't read. Let's take another look at the Field Artillery Magazine that the NYT referenced earlier in the editorial.

Clearance of fires was executed by demanding accurate company frontline traces and forward observer (FO) locations at regular intervals and battle tracking in detail.
...
Danger-close missions were the rule, not the exception. 2/A/1-6 FA, our Paladin platoon, and Thunder Base, our 120mm mortar platoon, quickly earned our confidence in their abilities to deliver timely and, more importantly, accurate fires. We routinely had 155mm and 120-mm fires within 200 meters of friendly forces.
...
As any combat training center (CTC) fight tells us, he who wins the reconnaissance fight will do well. Sergeant Sapp could destroy enemy OPs early and refine target locations as well as confirm or deny that targets we had planned were viable, such as AIF targets or buildings that did not appear to have been recently inhabited. (emphasis added)

US forces took care to avoid attacking civilian housing that had shown signs of being recently inhabited. This is the same publication that every WP critic is pointing to, because it mentions "shake and bake". And yet they will still accuse US forces of firing indiscriminately at civilians.

One last time: WP is not banned by Protocol III, it's use was in compliance with Protocol III, it's use in Fallujah isn't banned by the CWC, the Pentagon does not "refer to white phosphorus rounds as chemical weapons", it doesn't create a toxic cloud that kills everthing in a quarter mile, it doesn't burn flesh while leaving clothing intact, and most importantly, US forces did not fire indiscriminately at civilians, according to the very same source WP critics have been using to help support their nonsense.