Civilian population potential targets

That threat was the most potent argument against initiating chemical warfare. It drew its force from the fact that it was the civilian populations of the combatants who were the likely targets for retaliation. In addition, it was realised by all the combatants that once CW was embarked upon in one theatre of war, it would spread to others, complicating the conduct of operations at all levels. The potential costs of chemical warfare had so increased that the penalties of using it were extreme. 

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