White phosphorus is not banned by any treaty to which the United States is a signatory. Smokes and obscurants comprise a category of materials that are not used militarily as direct chemical agents. The United States retains its ability to employ incendiaries to hold high-priority military targets at risk in a manner consistent with the principle of proportionality that governs the use of all weapons under existing law. The use of white phosphorus or fuel air explosives are not prohibited or restricted by Protocol II of the Certain Conventional Weapons Convention (CCWC), the Convention on Prohibitions or Restrictions on the Use of Certain Conventional Weapons which may be Deemed to be Excessively Injurious or to have Indiscriminate Effects.
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Phosphorus is an element, the name derived from the Greek "phosphoros" or light bearing, the ancient name for the planet Venus when appearing before sunrise. Brand discovered phosphorus in 1669 by preparing it from urine. Phosphorus exists in four or more allotropic forms: white (or yellow), red, and black (or violet). Ordinary phosphorus is a waxy white solid; when pure it is colorless and transparent. White phosphorus has two modifications: alpha and beta with a transition temperature at -3.8oC. It is insoluble in water, but soluble in carbon disulfide.

Never found free in nature, Phosphorus is widely distributed in combination with minerals. Phosphate rock, which contains the mineral apatite, an impure tri-calcium phosphate, is an important source of the element. Large deposits are found in Russia, in Morocco, and in Florida, Tennessee, Utah, Idaho, and elsewhere.

White phosphorus may be made by several methods. By one process, tri-calcium phosphate, the essential ingredient of phosphate rock, is heated in the presence of carbon and silica in an electric furnace or fuelfired furnace. Elementary phosphorus is liberated as vapor and may be collected under phosphoric acid, an important compound in making super-phosphate fertilizers.



I presume the refernce to EM weapons was the sonic effect tests. But I can see that it is much better just to kill them, than to try to keep them from killing you by other means.