Jim, Israel's side of the story from your first link,
"These shells were used for specific operational needs only and in accord with international humanitarian law. The claim that smoke shells were used indiscriminately, or to threaten the civilian population, is baseless."

The Guardian view as stated in that link,

"White phosphorus burns in contact with oxygen and causes deep burns when it touches human skin, sometimes reaching to the bone. The weapon is not illegal itself and can be used to provide a smokescreen on the battlefield or as an incendiary weapon against a military target. However, its use is regulated even by customary international law."

The munitions used were smoke generating, not incendiary weapons.