This is coolbert:
I had forgotten all about this one. VERY germane considering the most recent allegations the Syrian central government of the dictator Assad waging chemical warfare against his own populace.
From almost five decades ago now another alleged but perhaps not so alleged use of poison gas.
The Yemeni civil war. Interventionist Egyptian forces accused of using poison gas on a number of occasions, Yemeni tribesmen neither understanding or prepared in the slightest manner for chemical warfare the target. Chemical warfare not on an unlimited and widespread basis, but nonetheless occurring.
From that wiki entry:
"The first use of gas took place on June 8, 1963 against Kawma, a village of about 100 inhabitants in northern Yemen, killing about seven people and damaging the eyes and lungs of twenty-five others . . . There were no reports of gas during 1964, and only a few were reported in 1965. The reports grew more frequent in late 1966. On December 11, 1966, fifteen gas bombs killed two people and injured thirty-five. On January 5, 1967, the biggest gas attack came against the village of Kitaf, causing 270 casualties, including 140 fatalities.The target may have been Prince Hassan bin Yahya [Royalist], who had installed his headquarters nearby."
"On May 10 , the twin villages of Gahar and Gadafa in Wadi Hirran, where Prince Mohamed bin Mohsin [Royalist] was in command, were gas bombed, killing at least seventy-five . . . The gas attacks stopped for three weeks after the Six-Day War of June , but resumed on July, against all parts of royalist Yemen. Casualty estimates vary, and an assumption, considered conservative, is that the mustard and phosgene-filled aerial bombs caused approximately 1,500 fatalities and 1,500 injuries."
These poison gases to include choking, blister and perhaps blood agents [cyanogen bromide]?
Poison gases NOT as necessarily sophisticated and deadly as nerve agent but very effective against Yemeni tribesmen totally unprepared and unequipped.
Since that time of the Great War [WW1] the major world powers possessing poison gas with the exception of the Japanese and Italians have employed chemical munitions on a limited basis and very discretely only when the circumstances were felt to be favorable, detection and retaliation highly unlikely.
DURING THAT TIME OF THE SIX DAY WAR  THAT EGYPTIAN MILITARY STATIONING AT LEAST HALF OF THEIR COMBAT FORCES IN YEMEN. THE EGYPTIAN WILLING TO USE POISON GAS OF OBVIOUS CONCERN TO THE ISRAELI, A CONSIDERATION TAKEN INTO ACCOUNT BY THOSE MILITARY PLANNERS IN TEL AVIV?