The United States agreed to destroy its mustard chemical agent in 1997 . The chemical agent is commonly called mustard gas despite being a liquid . almost 800,000 artillery shells are being destroyed over the next four years . The United States stockpiled almost 3,000 tonnes of the liquid .
The United States agreed to destroy its mustard chemical agent in 1997 . The chemical agent is commonly called mustard gas despite being a liquid . Almost 800,000 artillery shells are being destroyed over the next four years . The United States stockpiled almost 3,000 tonnes of the liquid .