The US has long stored a considerable arsenal of illegal-to-use chemical weaponry—until now. On Friday, the Pentagon destroyed its last remaining such weapon, the culmination of a decades-long effort, reports NPR. The dismantling took place at the Army's Pueblo Chemical Depot in Colorado and at the Blue Grass Army Depot in Richmond, Kentucky, per the AP. The outlet notes that the American military's chemical stockpile was up to 30,000 tons when the Cold War ended in 1991. The historic milestone now in place: All of the world's publicly declared chemical weapons—laden with everything from mustard gas to sarin—are now eliminated.
The US technically had until the end of September to complete the task of destroying the weapons in compliance with the 26-year-old Chemical Weapons Convention. It was the last of eight countries to eliminate its declared stockpile. "This is the first time, globally, that an entire class of weapons of mass destruction" has been destroyed, said Vietnam War veteran Craig Williams, who has been advocating for the safe destruction of the chemical arsenal since 1984, per the Lexington Times. Of course, the destruction covers only the declared chemical weapons in the world—other nations, including Russia, Syria, and North Korea, are believed to have undeclared stashes. (More chemical weapons stories.)