All of the the world's governments will, at least officially, be out of the chemical weapons business. The US Army tells The New York Times it should finish destroying the world's last declared chemical weapons stockpile as soon as tomorrow, July 7th. The US and most other nations agreed to completely eliminate their arsenals within 10 years after the Chemical Weapons Convention took effect in 1997, but the sheer size of the American collection (many of the warheads are several decades old) and the complexity of safe disposal left the country running late.
The current method relies on robots that puncture, drain and wash the chemical-laden artillery shells and rockets, which are then baked to render them harmless. The drained gas is diluted in hot water and neutralized either with bacteria (for mustard gas) or caustic soda (for nerve agents). The remaining liquid is then incinerated. Teams use X-rays to check for leaks before destruction starts, and they remotely monitor robots to minimize contact with hazardous material.
The Army initially wanted to dispose of the weapons by sinking them on ships, as it had quietly done before, but faced a public backlash over the potential environmental impact. Proposals to incinerate chemical agents in the 1980s also met with objections, although the military ultimately destroyed a large chunk of the stockpile that way.
The US last used chemical weapons in World War I, but kept producing them for decades as a deterrent. Attention to the program first spiked in 1968, when strange sheep deaths led to revelations that the Army was storing chemical weapons across the US and even testing them in the open.
This measure will only wipe out confirmed stockpiles. Russia has been accused of secretly making nerve gas despite insisting that it destroyed its last chemical weapons in 2017. Pro-government Syrian military forces and ISIS extremists used the weapons throughout much of the 2010s. This won't stop hostile countries and terrorists from using the toxins.
Even so, this is a major milestone. In addition to wiping out an entire category of weapons of mass destruction, it represents another step toward reduced lethality in war. Drones reduce the exposure for their operators (though not the targets), and experts like AI researcher Geoffrey Hinton envision an era when robots fight each other. While humanity would ideally end war altogether, efforts like these at least reduce the casualties.