Israel signed the 1993 Chemical Weapons Convention (CWC), but didn't ratify it. It never signed the 1972 Biological Weapons Convention (BWC). Its policy is CBW ambiguity.
In 1993, the US Congress Office of Technology Assessment WMD proliferation assessment included Israel as a nation having undeclared offensive chemical warfare capabilities. In 1998, former Deputy Assistant Defense Secretary Bill Richardson said:
"I have no doubt that Israel has worked on both chemical and biological offensive things for a long time. There's no doubt they've had stuff for years."
Israel tests new weapons in combat. Against Lebanon in 2006 and Gaza during Cast Lead, it used direct energy weapons, chemical and/or biological agents, and others producing injuries and symptoms medical professionals never previously saw.
For example, bodies with dead tissue had no apparent wounds. Corpses were found shrunken. Civilians had heavy lower limb damage requiring amputations. Nonetheless, unstoppable necrosis followed (death of cells and living tissue) followed by death.
Internal wounds had no trace of shrapnel. Corpses were blackened but not burned. Some badly wounded victims didn't bleed. The Palestinian health ministry said Israel used a new type explosive in Gaza. It contained toxins and radioactive materials. They burned and tore victims' bodies from the inside. They also left long term deformations.
A Palestinian doctor accused Israel of using chemical ammunition that burns and injures soft tissue, but can't be traced by X-rays. Severe internal wounds were reported. Unknown gases believed to be nerve agents were used. Those affected lost consciousness for about 24 hours. They experienced high fevers and muscle rigidity. Some needed urgent blood transfusions.
In Gaza, white phosphorous was used. It burns flesh to the bone. Depleted uranium spread radioactive contamination. Close-range explosives caused severe injuries, requiring amputations. Children had legs cut off, abdomens sliced open, or died because nothing could save them.