White phosphorus versus chemical weapons

Some critics of the USA are claiming that white phosphorus (WP) is a chemical weapon.

Critics claim that the US used chemical weapons in Falluja, on the grounds that it is the toxic properties which cause the harm. The UK's Guardian newspaper for example said: "The US used chemical weapons in Iraq - and then lied about it."

However, if WP counts as a chemical weapon, then Iraq was openly in possession of chemical weapons in 2002, thus validating the U.S. administration's claim that Iraq possessed chemical weapons. From a 2004 CIA report on Iraqi WMD:

Hutin Munitions Production and Storage Facility: ISG discovered numerous barrels (over 3,000 gallons) of white phosphorus and munitions assembly lines, which we judge were intended for the production of white phosphorus illumination rounds. This white phosphorus, probably imported and declared by Iraq in 2002, could have been used to produce some nerve agent precursors on a laboratory scale.

It's worth noting that the CIA did not claim the WP located to be a chemical weapon and therefore a "slam dunk". If, however, WP is a chemical weapon, then Saddam was technically in possession of chemical weapons in 2002, thus validating the U.S. adminstration's case for invasion.