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A drawing of a large hourglass surrounded by bottles of chemicals and vapors. Niv Bavarsky for Vox

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2023 was the year the US finally destroyed all of its chemical weapons

The world banned chemical weapons in 1997. Here’s why it took so long for the US to eliminate its arsenal.

Jen Kirby is a senior foreign and national security reporter at Vox, where she covers global instability.

The United States’s Chemical Warfare Service readied hundreds of thousands of mortar shells and artillery rounds filled with mustard gas in the 1940s. During the Cold War, even more lethal chemical weapons followed: artillery and rockets filled with VX and GB, better known as Sarin, nerve agents that, with as little as a few drops, can be deadly.

These munitions would make up the United States’s chemical weapons arsenal, one of the biggest in the world.

It’s all gone now. This summer, on July 7, at the Blue Grass Chemical Agent-Destruction Pilot Plant in Kentucky, the last M55 rocket, filled with GB, was dismantled. With it went the entirety of the US’s declared chemical munitions stockpile.

The United States achieved this just shy of its September 30 deadline under the Chemical Weapons Convention (CWC), the 1997 international treaty that bans the production, use, and stockpiling of these weapons. The US was the last country party to the treaty to eliminate its declared chemical weapons stockpile, destroying the kinds of agents and munitions once hoarded for use on the battlefield.

The world still has chemical weapons — in countries that never signed the treaty, scattered in old war zones, and likely in nations that have broken their treaty promises.

But the US certification is still a huge achievement for America, and for the world.

The US had some 30,000 tons of chemical warfare agents at the time of the CWC ratification. The US learned quickly that agreeing to eliminate chemical weapons was one thing. Actually doing so was far more complex. “These are weapons that were built to be used, not destroyed,” said Sonia Ben Ouagrham-Gormley, an expert in weapons programs and an associate professor at George Mason University.

That treaty effort stretched more than 25 years, though the US had grappled with how to dismantle its arsenal safely and effectively even before that. The US wasn’t alone in needing extensions under the CWC, but the American experience was uniquely lengthy and complicated.

Local, state, and federal lawmakers all got involved, as did environmental and community activists who questioned and challenged how the US Army planned to destroy toxic agents in the places where they and their families lived. It was akin to a “not in my backyard” movement with something close to existential stakes. These organizers used their protests to create new policies and influence the technology and methods used to destroy these munitions. Early opponents became community watchdogs for a global agreement so that the treaty’s mission — the safe elimination of an entire class of weapons — reflected the desires of the public it was intended to protect.

These debates and delays weren’t exactly predicted when countries signed on to the Chemical Weapons Convention, but they helped reveal one of the biggest challenges of disarmament: The decision to produce weapons of mass destruction is not easily unraveled or undone. Chemical munitions were designed to kill, not to be disassembled and decontaminated. It took decades to eliminate America’s chemical weapons arsenal because, as dangerous as these weapons are to make and to store, they are all that much harder to destroy.

Craig Williams remembers the US Army hosting members of the local community for a meeting in February 1984 on the grounds of the Blue Grass Army Depot in Richmond, Kentucky. About 300 people showed up. “The Army got up,” Williams, the co-chair of the Kentucky Citizens’ Advisory Commission, recalled, “and they explained that there were chemical weapons stored on the facility’s grounds, and they planned to dispose of them by incinerating them. And did anybody have any questions?”

Many people had many, many questions, Williams said. For good reason. Blue Grass was one of nine chemical weapons depots maintained by the United States (there were eight within the continental US and one on Johnston Atoll in the Pacific). Communities like Williams’s knew of these military facilities, but what was being stored in those lumps on the landscape wasn’t widely advertised. Many found out about the chemical weapons close to their neighborhoods when the Army said it wanted to destroy them.

Factory machinery disassembling a mustard-gas-filled shell.
Pueblo Chemical Depot, pictured here in 2016, finished neutralizing the last 155mm shells filled with mustard gas this summer — decades after the US first started thinking about how to destroy its arsenal.
Joe Amon/Denver Post via Getty Images

Williams had just collided with the start of the latest, maybe most contentious, chapter of the US’s efforts to maintain its chemical weapons stockpile, one that began nearly a decade before the CWC even opened up for signatures.

The United States used chemical weapons in World War I, though they were foreign-made munitions from its allies. That use of poisonous gas on European battlefields helped prompt countries to create the Geneva Protocol of 1925, which banned poisonous gasses and biological agents in war. The US did not sign on at the time and continued researching and developing chemical weapons, although it wasn’t a huge priority for the military until World War II. Washington did not deploy chemical munitions in World War II, though it “had supplies of agents and equipment with which they could have waged warfare energetically if necessary,” according to The Chemical Warfare Service: From Laboratory to Field.

Most of those World War II-era weapons were blister agents, like mustard, which can cause burns or blisters, damaging the eyes or lungs; they were intended to slow enemy troop movements. During the Cold War, the US began experimenting with nerve agents in rockets and artillery, things like GB that, when released, acted fast and were almost assuredly lethal.

Both the US and the then-Soviet Union ultimately built huge chemical stockpiles, each with, at points, an estimated 30,000 to 40,000 tons of chemical agents.

By the early 1960s, though, these weapons started to fall out of favor in the US. America still felt it necessary to have chemical weapons in case the USSR used them, but the Cold War emphasis was on America’s nuclear arsenal. There were also some public mishaps — like an alleged open-air VX test in Utah that killed or injured thousands of sheep — and public anger over the use of herbicides like Agent Orange during the Vietnam War, which created lasting harm and health issues for both US veterans and civilians in Vietnam, Laos, and Cambodia.

These forces helped push Congress to pressure the Nixon administration to review the entirety of the US biological and chemical weapons programs. In 1969, Nixon renounced biological weapons — eventually leading to an international treaty banning those — and the US reiterated a no-first-use policy for lethal and incapacitating chemicals (meaning, Washington would only use them if Moscow did first) and halted the production of new chemical weapons.

Yet it wasn’t as simple as hitting pause. All weapons have a shelf life, and chemical munitions are no exception. They age, they degrade, they can leak. You can’t just put them in storage and forget about them. Maintaining an adequate arsenal also requires disposing of its faulty components.

The solution was mostly the sea. In the late 1960s, the US undertook Operation CHASE (“Cut Holes and Sink ’Em”). It is what it sounds like: Load a bunch of chemical weapons or ammunition on an old ship and sink it all. The other options, though, were worse: burning chemical weapons in the open air or burying them on land.

These operations also started to come under scrutiny amid a growing environmental movement. In the 1970s, Congress more tightly regulated the disposal of chemical weapons, forcing health and safety reviews, and eventually outlawing the sea dumps. This solved one problem but not the other: a bunch of old, crumbling chemical weapons, sitting in storage.

Which was the Army’s dilemma when it showed up near Williams’s hometown. By that point, in the 1980s, the Pentagon said the US stockpile was barely usable. The munitions didn’t work with the current-day launchers. It was all a bunch of crap, albeit very, very dangerous crap that needed to be closely monitored.

The military’s plan was to replace the old stocks with a “binary” chemical munition. It sold these newer weapons as a more stable, “safer” version because instead of filling up an artillery shell with a lethal toxin, these munitions separated the chemical compounds so that they became a deadly nerve agent only after being fired, making them easier to transport, store, and, if necessary, get rid of.

Congress was less convinced. The US had stopped producing new chemical weapons and now indicated it wanted a worldwide ban. The Pentagon proposed upgrading an arsenal the US had by now promised it would never use.

Lawmakers found a kind of compromise: For every new binary weapon the military wanted, it would have to get rid of one old munition first.

The Army had already begun piloting methods of destroying chemical weapons at this point. One was incineration, which uses very, very high temperatures to destroy the chemical agent (and also treat the munition). The Army began employing on a small scale starting in the 1970s.

Now the Army planned to scale up incineration. And when the military told people who lived near these chemical depots what they proposed to do, a lot of people in those communities thought some version of: You’re going to do what with what? Where?

Williams felt the Army didn’t have any satisfactory answers when he and others pressed it on the mechanics of incineration. “Simple things like, you know: What comes out of the stack? How does the technology work?” Williams recalled. “And they were like, well, just, you know, ‘Trust us.’”

This sense of distrust and skepticism existed elsewhere, too, in addition to the fear that the Army wasn’t listening to their concerns about possible pollution or health effects.

Rufus Kinney, an activist in Alabama, joined protests, including a ribbon-burning with civil rights leaders at the chemical depot site in Anniston, Alabama. As Kinney noted, the depot was near a predominantly Black neighborhood that had been poisoned for decades by Monsanto; why would this time be different? In Pueblo, Colorado, home to another depot, Irene Kornelly, chair of the Colorado Citizens’ Advisory Commission, recalled how farmers and ranchers worried about the possibility of tainted food supplies.

A worker in protective clothing stands in a special storage area filled with M-55 rockets armed with sarin gas at an incinerator on June 12, 1995, at the Tooele Army Depot — one of the locations that used incineration to destroy the US’s arsenal.
Remi Benali/Getty Images

And it made some sense: Incineration called to mind industrial processes with smelly stacks puffing out dark smoke. The process to destroy chemical weapons was not the same as “take trash from the local community and throw it in and burn it up,” said Michael Greenberg, a professor emeritus at Rutgers and a member of the National Research Council Committees that consulted on the destruction of the US chemical weapons stockpile.

The incinerators expose toxic agents to very, very, very high temperatures, and through a series of steps, the end product becomes harmless. Incineration was the Army’s preferred method of disposal. They argued it could be tightly controlled and regulated and prevented the possibility of any chemical agent re-forming. The process included safeguards to protect workers and communities, such as stringent monitoring protocols and airflow systems that prevented chemicals from being released.

But many activists said they didn’t feel as though their concerns were adequately addressed: What if something went wrong in the process? The military may be monitoring what’s being released, but how confident should affected communities be that everything was being detected?

The Army essentially told people, “‘We’re the technical experts so you need to follow our direction,’” said Robert Futrell, professor of sociology at the University of Nevada-Las Vegas, who has researched the destruction of chemical weapons and grew up near the Blue Grass depot. “But there’s a question that I think the citizens were raising as well: ‘You might be the technical experts, but are you asking all the right questions?’”

As this was unfolding at home, the United States was getting out of the chemical weapons game altogether at the international level. The US and the USSR negotiated an arms control agreement on chemical weapons, signed in 1990, in which they agreed to make no new weapons and drastically reduce their stockpiles by 2002.

This brought momentum to a global treaty. The CWC opened for signatures in 1993. It prohibited the production, development, and use of chemical weapons, and notably included a robust verification and inspection regime. The US and Russia both signed. More than 190 states are now party to the treaty.

The CWC went into force in 1997. It was a huge global accomplishment, the outlawing of an entire class of weapons, one considered uniquely dangerous and horrific. Unlike the Biological Weapons Convention before it, countries agreed to robust verification metrics, such as on-site inspections, including of industry, to prevent any materials from being repurposed for weapons use.

President Bill Clinton standing at a lectern outdoors at the White House.
Then-President Bill Clinton discusses the importance of ratifying the chemical weapons convention treaty.
Scott J. Ferrell/Congressional Quarterly/Getty Images
Senator Biden speaking and holding up a piece of paper.
Then-Sen. Joe Biden speaks at a 1997 Senate Foreign Relations Committee hearing on chemical weapons.
Douglas Graham/Congressional Quarterly/Getty Images

A major part of the CWC involved eliminating those declared arsenals. Countries came forward to say how many chemical munitions or bulk agents they possessed. The CWC set the initial deadline for destruction for all declared stockpiles by 2007, though multiple countries got extensions, most notably the US, which eventually received this 2023 deadline. Only a handful of states declared their stockpiles when they joined the CWC: Albania, India, Libya, Syria, Iraq, an anonymous state that is widely believed to be South Korea, and the US and Russia.

But it was really all about Russia and the US, said Al Mauroni, director of the US Air Force Center for Strategic Deterrence Studies, who spent decades in the Pentagon working on chemical weapons issues. Other countries had much smaller arsenals; India, for example, had about a thousand metric tons of sulfur mustard; Albania, the first state to destroy its stockpile, had about 16 metric tons — still an order of magnitude smaller than either of the two superpowers.

“There was a subtext to the treaty, very much to say the reason we’re having this discussion is because Russia and the United States have really big chemical weapons stockpiles,” Mauroni said.

As the world moved toward banning chemical weapons in the 1990s, US activists also started to see their fight in more international terms. In 1990, in Kentucky, Williams helped organize a gathering of leaders from community leaders tied to the chemical weapons depots around the country and from other nations about to undertake their own destruction processes, including Russia.

They formed the Chemical Weapons Working Group (CWWG). Together they developed a citizens’ accord on chemical weapons destruction. “We were collectively trying to protect communities all over the place where this material was stored and where they planned on incinerating,” Williams said.

That accord, Williams said, marked “the transition from ‘not in my backyard’ to ‘not on planet Earth.’”

The Chemical Weapons Working Group was adamantly opposed to the Army’s method of incineration, but they wanted the weapons gone, too, so they had to figure out what would work. They raised funds to hire experts to study alternatives. They came back with their own plans and proposals. They pursued lawsuits. They lobbied lawmakers.

“The pushback was not just pushback,” said Ben Ouagrham-Gormley. “It meant creating committees with localities to discuss the different technologies, investing time and money in investigating different technologies, and also looking at the environmental impact of the technologies.”

“All that took several years and pushed the deadline further because without a clear design or clear acceptance of a certain technology by the localities, then there was no way to start the destruction.”

A few things happened as a result. The activists became enough of a force that the Army realized that if it wanted to destroy the weapons, it needed communities on its side, not as antagonists. The Army got better at public relations. It began holding more public hearings where Army representatives explained their approach in more detail. It gave money to local communities for additional safety precautions: gas masks and radios, in case something went wrong. They installed sirens, trained local hospital staff, and added safety measures and protocols.

The Army “put a lot of effort into making sure that the states felt comfortable, that they would be part of the management of an incident if something were to go wrong, which never happened,” Mauroni said.

Yet the Army had moved ahead with construction for an incinerator at Tooele, Utah, where a huge chunk of the US’s chemical weapons arsenal was stored. The plant began burning weapons via incineration in 1996.

With Tooele up and running, the Army began planning construction at other facilities. Activists and environmentalists in those communities did not give up, and continued to fight, threaten lawsuits, and lobby lawmakers. In 1996, Congress created the Assembled Chemical Weapons Assessment (ACWA) program, which required the identification and testing of at least two alternative ways to destroy chemical weapon. The activists had finally prevailed.

Neutralization became the chosen alternative process. This wasn’t a new technology, exactly; the Army had also tested this process in the past to destroy chemical weapons, just never scaled it up because the military preferred incineration.

But activists saw this as a safer, more sound alternative. With neutralization, the munitions are disassembled, with the explosive and the chemical agent removed. The metal in the munition is blasted with very high heat to make sure all the chemical agent is eliminated, and then it’s recycled — into railroad tracks or car parts.

The chemical agent, meanwhile, goes through a bunch of tanks, where it’s heated, agitated for several hours, and then gets a dose of sodium hydroxide, which triggers a chemical reaction that turns the lethal agent into a non-deadly one. That mixture is sampled — just to make sure it’s all okay — and then it goes through a biotreatment process; that is, a bunch of microbes eat up any leftover compounds.

An employee at the Pueblo Chemical Depot, one of two locations to ultimately use neutralization, is seen here in 2016 lifting shells onto the projectile/mortar disassembly system.
Joe Amon/Denver Post via Getty Images

It took a while to get there, though. ACWA studied new technologies and tested them, and it also got other stakeholders involved: local government, public health authorities, and the community. “Now you’ve got to build a whole facility that can manage all the chemicals, test it, and then get it into operations, and that took a lot longer than anybody had intended,” Marouni said.

Two sites — in Pueblo, Colorado, and Blue Grass, in Kentucky — piloted the neutralization process to destroy their stockpiles of chemical weapons. They are the same two sites that finally disposed of all their weapons this summer.

These local activists achieved an alternative method to destroy chemical weapons. But depending on who you ask, this was either an incredible accomplishment by passionate communities or a long, drawn-out roadblock — and then there is the complicated, muddy middle.

“That’s why it took such a long time,” Greenberg said of the destruction process. “And you know what? Both sides were right. And both sides were wrong.”

The military favored incineration as its preferred method and pointed out that they executed it safely in all of the sites where it happened. (Though there were scares along the way.) It remains an accepted method for chemical weapons destruction under the CWC. About 90 percent of the nation’s chemical weapons stockpile was destroyed by about 2012, primarily through incineration, though that last 10 percent, destroyed largely through neutralization at Pueblo and Blue Grass, took another decade.

But activists, and many experts, see the value in the community pushback. For one, the chemical weapons activists brought public and government attention to such a sensitive issue. Many of the early antagonists to the chemical weapons destruction plans, like Williams, became the leaders of the citizen advisory commissions that served as the main way for depot staff, officials, and citizens to share information on the destruction processes.

“We wanted to get rid of the weapons,” Williams said. “We just wanted to do it in a way that prioritized public health and environmental protection and that involved the input of the communities impacted. That was our mission. We didn’t waiver from that.”

By forcing the United States to seek out alternatives, these activists helped influence the way the world destroys chemical weapons. Neutralization is “much more controllable, and doesn’t release anything to the atmosphere,” said Paul Walker, vice chair of the Arms Control Association and coordinator of the CWC Coalition. It’s also more nimble, and mobile. The US deployed a version of neutralization technology as part of the international effort to destroy Syria’s stockpile of chemical weapons in 2014, which took place on ships at sea. “Not only did they change the process of participation, and that moved all the way out to shaping international treaties, they also changed technology,” Futrell said.

For many environmentalists and activists, concerns about incineration never went away. Some activists who live in communities where incineration took place are still frustrated, though proud they helped achieve an alternative elsewhere. “I’m grateful the chemical weapons are gone,” said Cindy King, an activist near the Tooele, Utah facility that incinerated weapons. “But at what expense? Did they have to be gone the way they did?”

Overall, the chemical weapons destruction process in the US was extraordinarily safe, which was never guaranteed. That there have been no accidents, no leaks, no casualties in the multi-decade process is remarkable. “Our safety profile in this industrial, very toxic area is equal to a banking system,” said Michael Abaie, a top Pentagon official involved in the Program Executive Office for Assembled Chemical Weapons Alternatives. “Wrap your brain around that.”

“No munitions have ever been designed to be taken apart,” Abaie said. “That was one of the biggest challenges that we ever took on.”

When the military made these weapons decades ago, their concern focused on how they might work on the battlefield, what they might do to the enemy, and what their existence could prevent the enemy from doing to us. No one thought of what it might take to get rid of them. “It was an extraordinarily dangerous and complicated effort, and we saw it through to the end,” said Andy Weber, senior fellow at the Council on Strategic Risks and a former Pentagon official overseeing chemical and biological risks.

In hindsight, the CWC’s initial destruction timeline was very ambitious, set by a bunch of diplomats who maybe didn’t fully understand what it would take. But this is what the spirit of disarmament is about, says Alexander Ghionis, research fellow in chemical and biological security at the University of Sussex. “You’ve got to set ambitious goals when the atmosphere is good. And diplomacy was moving in the right direction.”

The necessary requests for the US extensions were done in consultation and approved by the Organization for the Prohibition of Chemical Weapons (OPCW), the group that oversees and implements the CWC. Inspectors were on site at the chemical depots, observing the destruction of every single munition — via cameras, of course.

A lot of this happened because the CWC is one of a kind: a near-universal disarmament treaty that has real heft behind it. The OPCW, which today has an estimated 2023 budget of around $80 million and some 500 staff members, was created to oversee implementation and inspections. It also bans specific substances, which makes it harder to circumvent. “Other than the Non-Proliferation Treaty, it’s the only one that is still being actively implemented worldwide from a verification [standpoint] and from otherwise ensuring people meet their obligations,” said John Gilbert, a retired US Air Force colonel and senior science fellow with the Center for Arms Control and Non-Proliferation’s Scientists Working Group.

Syria Civil Defence (White Helmets) members lit candles this August to commemorate the 10th anniversary of the Ghouta chemical attack, in Idlib, Syria — a reminder that th eworld is not yet truly free of chemical weapons.
Izzettin Kasim/Anadolu Agency via Getty Images

Now that the declared weapons stockpiles are gone, the goal is to make sure they don’t come back. That means keeping up with inspections and any scientific developments that could be used for chemical weapons. And the success of the CWC so far does not make it foolproof.

Some countries are in violation of the treaty. Syria used chemical weapons against its civilians in its civil war, and many experts and officials suspect the country has maintained some portion of its arsenal. Russia destroyed its 40,000-ton arsenal in 2017 under OPCW supervision, but it has used chemical agents in assassinations — for example, the nerve agent Novichok was employed in an attack on ex-Russian spy Sergei Skripal in 2018. At the time, it was not a banned substance under the CWC, but it became one in 2019, over Russia’s initial objections.

And there are still countries that are outside the CWC, including Israel and Egypt. North Korea is not a signatory to the treaty, and it definitely has chemical weapons; it is credibly believed to have used VX in an assassination in 2017.

The world is also still dotted with remnants of old and abandoned chemical weapons. The OPCW is working with China and Japan to clean up old stockpiles left behind after World War II. A report from the 1990s assessed that there were chemical weapons buried in 215 sites in at least 33 states in the US. The world’s oceans are full of chemical weapons, especially in the Baltic and Mediterranean Seas, where vast arsenals were dumped after World War II. Those effects still linger today.

All of which means the world is still not fully free from the threat of chemical weapons. Even elimination comes with an asterisk; you just can’t unmake a huge weapon of mass destruction program. Even with the weapons now gone, the US depots that housed these chemical munitions will now have to go through a years-long decontamination and decommissioning process Even when they’re repurposed, the options for their use will be limited because those weapons were stored there for so long.

Chemical weapons may now be less likely to be used as a tool of war, but the difficulty of the destruction process provides a warning. The tools of battle linger long after they are used; in Ukraine right now, unexploded artillery shells and land mines litter fields and communities. The chemical weapons created decades ago still pollute fields and seas; they may be fine for now, but for how long?

The norms of war shift and change. Chemical and biological weapons are now taboo weapons, but there are so many others — anti-personnel landmines, cluster munitions, nukes — that the world has tried to ban. It hasn’t fully yet, but it may, and what will happen to all those rounds and rounds in storage? “You shouldn’t build [weapons] to be used on the battlefield only,” Walker said. “You should design into them ways to recycle them.” Countries invest and prepare for war, but in doing so, they should also make it easier to prepare for peace.

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