Terrorist organizations in Afghanistan want to systematically eliminate United Nations forces from each location in Afghanistan and know that small

Terrorist organizations in Afghanistan want to systematically eliminate United Nations forces from each location in Afghanistan and know that small arms fire and high explosives, although effective, will fall short of forcing enemy troops to leave; however, they have tons of sarin gas that could, if properly placed and activated, based on the prevailing winds, effectively destroy the troop concentrations in each location; especially if simultaneous attacks were unleashed across the country.

How can we mitigate such attacks and develop strategies to prevent such attacks or at least properly respond to diminish the effects of the gas?