It’s being destroyed under a 1997 international treaty banning all chemical weapons. Most of Pueblo’s stockpile will be dismantled and neutralised in a highly automated 4.5 billion US dollar plant built at the depot and it will take four years to destroy this stockpile.
Another 523 tons of mustard and deadly nerve agents are stored at Blue Grass Army Depot in Kentucky. Blue Grass isn’t expected to start destroying its weapons until 2016 or 2017, finishing in 2023.
The US acquired 30,600 tons of mustard and nerve agents, but it never used them in war. Nearly 90 percent of its original stockpile has already been destroyed.