It appears after 2003 invasion of Iraq, Bush administration covered up the discovery of chemical weapon facilities in Iraq that was abondoned in 1991 because stories of abandoned weapon facilities contradicted Bush administration's bogus jusification of war.
As a result, data of chemical stockpiles in those facilities were not shared with occupation troops. So some unaware troops were accidentally exposed, given inadaqaute treatment, and told to never talk about it. Worse, since the facilities and stockpiles were not disclosed to relevent agencies and troops, they were not destroyed.
Once such stockpile recently fell into the hands of ISIS.
NYT article.
As a result, data of chemical stockpiles in those facilities were not shared with occupation troops. So some unaware troops were accidentally exposed, given inadaqaute treatment, and told to never talk about it. Worse, since the facilities and stockpiles were not disclosed to relevent agencies and troops, they were not destroyed.
Once such stockpile recently fell into the hands of ISIS.
NYT article.