The demilitarisation of chemical weapons

Since the dawn of chemical warfare in the First World War, various countries in the world made large quantities of chemical warfare agents (the toxic chemicals themselves) and chemical munitions (the weapon systems to dispense them). Only a portion of these weapons were used on the battlefield and no country has a declared arsenal of chemical weapons now, although a few arms control hold-outs might have a few stashed away. Where did they go? The answer is both interesting and alarming.

It is nearly a fool’s errand to try to calculate how many tonnes of chemical warfare agents were manufactured during the 110 years since their first major battlefield use at Ypres in World War I. Many records are still secretive, but the quantity has to be well into the hundreds of thousands of tonnes of agents and accounts vary considerably. Many accounts mistakenly confuse munition weight (the weight of a filled bomb or shell) with agent weight (just the weight of chemicals), and many countries also ended up with unfilled munitions at the end of wars, thus further complicating the accounting.

The end of wars, the obsolescence of a particular chemical agent or delivery system, the end of the Cold War, and the worldwide adoption of arms control treaties, principally the Chemical Weapons Convention (CWC) adopted in the 1990s, gave impetus to the destruction of both chemical agents and munitions, both filled and unfilled. The process of disposal gradually became known as ‘chemical demilitarisation’ and it has taken on many forms over the years. This article relies more heavily on US demilitarisation efforts, as they are exceedingly well-document in the public domain, unlike efforts in other places. The American experience heavily documented many of the technical and environmental problems, leading to an extensive body of knowledge in this otherwise arcane field.

Chemical demilitarisation has been harder than getting rid of other classes of weapons. Swords can be literally turned into ploughshares if someone wanted to do it, and tanks and battleships can be scrapped for metal. Tonnes of nerve agent or similar chemicals, however, present different sorts of problems. The vast majority of chemical warfare agents and munitions were developed with a view towards battlefield use, but not with any sort of idea how to get rid of them when no longer needed. Some chemical warfare agents will leak or degrade, but others could easily last many decades in undisturbed intact munitions. On top of the problem of weapons no longer wanted or needed, there are issues with lost or abandoned chemical weapons. Ships sink, entire countries go out of existence, and chemical weapons fail to function, and so sit alongside other unexploded remnants of warfare.

Out of sight, out of mind

The first approach taken was burial. Both Western and Eastern fronts in the First World War saw extensive use of chemical weapons. The initial impetus was to leave potentially unexploded defective weapons buried in situ, often out of lack of any better idea. Given the technology of the time, this was, if not a good idea, a ‘least bad’ idea in many people’s minds. The legacy of such decisions in 1918 and 1919 still rears its head, with chemical artillery shells still occasionally turning up in fields in France and Belgium.

Larger quantities of chemical munitions were simply buried in trenches. This was very much an approach taken by the Japanese at the end of the Second World War in China, as they were retreating in haste and their government no longer existed. China was by no means the only exemplar of such haste. The US Army, for example, buried numerous munitions just outside Washington DC only to be uncovered by construction in the leafy neighbourhood of Spring Valley in the 1990s, leading to an expensive clean-up effort that dragged on for many years. These instances cannot be considered a demilitarisation strategy in themselves, and merely deferred the problem for later generations.

Get in the sea!

Up until the 1960s, environmental impact was not foremost in the mind of governments seeking to get rid of munitions. The easiest course of action for getting rid of larger quantities of chemical weapons was to sink them in the sea. It is likely that the most widespread disposal effort, at least up until about 1970, was disposal at sea. Even at the time, these disposal operations were considered the least bad of poor options, but not ideal.

People could be forgiven for imagining that ‘getting rid of chemical weapons in the sea’ was basically pouring the chemicals straight into the water. This did not happen at any significant level. Dumping of whole munitions (for instance, chemicals inside a shell or bomb) did happen, but the state of the art for sea disposal was to place the munitions in surplus ships and then sink those vessels. For example, Operation Sandcastle saw the British military get rid of 71,000 captured German bombs filled with the nerve agent Tabun in 1955 and 1956. These were loaded on superannuated merchant vessels and sunk in the North Atlantic at a depth of 2500 m.

 

The most transparent and best-documented chemical demilitarisation campaign has been the US Army’s fifty-year effort to get rid of its Cold War chemical arsenal. President Nixon, for all his faults in other areas, was an earnest proponent of arms control and an advocate for chemical and biological disarmament. Long before the US military decided to fully rid itself of chemical weapons in the 1990s, there were numerous items that were no longer fit for purpose. The US Army, which was the custodian of all the US chemical weapons, started disposal operations quite early on, and gradually scaled them up. The US had a series of such operations called Operation CHASE which gloriously stood for ‘Cut holes and sink ‘em’. For some of the more dangerous US weapon systems, such as the infamously unsafe M55 nerve agent rocket, the US would put the rockets in steel boxes and fill the boxes with concrete, encasing the rockets in dense blocked of concrete, before loading them on ships. These ships would be sunk in deep sea, at a depth of thousands of metres.

Operation CHASE started to get significant opposition from residents and local politicians as, invariably, rail and road operations to move the chemical weapons from landlocked storage depots to sea ports raised the prospect of accidents or incidents. Sober risk assessments showed that transport was the most dangerous aspect of the operation, and increasing public concern for the environment meant that this programme ended. The last Operation CHASE sinking took place in August 1970.

Neutralisation or incineration

The Cold War drew to a close with vast arsenals of chemical weapons in the Soviet Union and the United States, with smaller stockpiles in several other countries. In the United States, the ending of sea disposal happened at the same time as President Nixon’s halting of chemical weapons production and a general pivot away from chemical warfare as a military doctrine. Various panels of scientists and chemical engineers contemplated the disposal problem and considered two approaches, neutralisation and incineration. Neutralisation adds chemicals to the warfare agents to degrade them into substances that are less dangerous. Incineration uses very high temperatures to cause the molecules to fall apart into much safer molecules.

The US had considerable experience using neutralisation with Sulfur mustard (so-called ‘mustard gas’) and Sarin, but only very limited experience with VX. Mustard could be mixed with chemicals such as monoethanolamine, but this would leave a sludge of by-products, some of which were almost as much of a disposal hazard as the original. Sarin was considered easier to destroy, and many hundreds of tons of Sarin were treated with sodium hydroxide. While effective, the chemical reaction was technically reversible, and some Sarin re-formed out of waste products, meaning that the waste would have to be incinerated anyway.

The US then pioneered high-technology high temperature incineration. A National Academy of Science study concluded that incineration was the only truly safe method. The method had much to recommend it, in that none of the decomposition products had any chance of re-forming back into warfare agents, the effluent could be easily monitored, and the emitted exhausted gases were well down the list of environmental hazards. Both in quantity and composition, the emitted compounds were far less damaging than a coal power plant, particularly the power plants of the era.

 

At first there was a pilot plant in Utah to pioneer various concepts, then, at vast expense, the large Johnston Atoll Chemical Agent Disposal System was built in the mid-1980s. Johnston Atoll is a US possession in the Pacific, some 1500 km southwest of Hawaii. One of the USA’s most remote places and with no local population to remonstrate, it had become the resting place for US chemical weapons withdrawn from Okinawa in 1971. These weapons were later joined by US Army chemicals withdrawn from Germany. By 1990, by the time the disposal incinerator went on line, Johnston Atoll had 262 tonnes of Sulfur mustard, 1197 tonnes of Sarin, and 383 tonnes of VX. It took a long time, but by 2000 the chemicals had been destroyed

The USA also had vast amounts of chemical weapons stored at eight sites in the continental USA, and had originally planned to ship them to Johnston Atoll. However, concerns about safety in transport nixed the concept, especially since some of the weapons were leaking. The laborious process of building destruction plants at those 8 sites and took decades. The entire campaign was beset by myriad delays too numerous to detail here. Some delays were technical; the M55 nerve agent rocket was a fiendish devil to destroy. A varied blend (local politics being very different across the US chemical weapons estate) of local activism and environmental litigation combined legitimate concerns, distrust of the Federal government, low probability worst-case scenarios that rightly alarmed the local populace, and the occasional conspiracy theory all combined to drag the programme out considerably. Ironically, environmentalism delayed the end of the US chemical weapons programme

The Federal government responded with a mix of dithering and diplomacy, lavishing large grants to the nearby communities mostly in the form of the Chemical Stockpile Emergency Preparedness Program. Many a local fire or police department benefited from Washington’s largesse. Incineration progressed at six of the eight storage sites, being completed in 2012, well over budget and well behind schedule.

Not everyone was happy with incineration. It was occasionally likened to simply burning in the open, although the high-tech methods were far from that, and decades of entrenched debate had sometimes devolved into hyperbole. In two locations, Pueblo, Colorado and Lexington, Kentucky, incineration was so vociferously opposed that the Army re-investigated neutralisation and under the label ‘Assembled Chemical Weapons Alternatives’ used more advanced chemical techniques than those available in the 1970s when the problem was previously considered. Although the programme was delayed and more expenses piled up, the last of the US chemical weapons stockpile was destroyed in 2022. The X (formerly Twitter) account of the Program Executive Officer for Assembled Chemical Weapons Alternatives provided a fascinating level of detail of the last years of this effort.

Finding CW in other places

The US experience is by no means the only one. Russia went to great lengths to destroy the old Soviet arsenal. In better political climes, this was heavily aided by US technical grants and expertise under the Cooperative Threat Reduction programme. Regardless of lingering doubts raised by incidents like the attempted assassination of Sergei Skripal with a nerve agent, thousands of tons of chemical agent were destroyed under international supervision.

Old or abandoned chemical weapons do crop up from time to time in places like France, Belgium, and China, left over from the World Wars. Specialist destruction facilities have been built to deal with such munitions when they are found. Albania found an old stockpile and did the right thing by declaring it. A small destruction plant was built and some USD 48 million spent to rid Albania of this unwanted legacy. Elsewhere, South Korea very quietly got rid of some chemical weapons at some point, although the programme was shrouded in secrecy. India declared and destroyed a small stockpile. An international effort led to the demilitarisation of a small Libyan programme.

Sometimes things still are not destroyed in an ideal way. US Army soldiers destroyed large quantities of Saddam Hussein’s chemical weapons at a storage complex in Khamasiyah, Iraq, in 1991. It was thought that ample quantities of high explosive would destroy the chemical agents, but the efficacy of the demolition was doubtful and the exhaust plume has been closely correlated to many medical problems. (This is discussed in more detail in the article on Burn Pits and Toxic Residue of War, forthcoming in this publication).

Syria acceded to the Chemical Weapons Convention after being caught using Sarin in 2013. A quantity of Sulfur mustard, some of it evidently quite old, and many tonnes of precursor chemicals were declared and offered up for destruction. Destroying them amidst an ongoing civil seemed problematic, but no country wanted to take the worst of the chemicals. The Organisation for Prohibition of Chemical Weapons (OPCW) and the USA, with some funding from the UK, deployed a merchant vessel, the MV Cape Ray, equipped with two ‘Field Deployable Hydrolysis Systems’ that used chemistry not dissimilar to that used in Pueblo, Colorado. The Cape Ray neutralised Syrian mustard and some nerve agent precursors while at sea in the Mediterranean. Syria’s ultimate compliance with chemical demilitarisation will only be determined after a full accounting of the former Assad regime’s chemical programme, now that the Assad regime is out of power.

There are future prospects in this area. Old munitions continue to turn up in Western Europe, China, and a few have turned up elsewhere over the years. At some point, the world may need to deal with possible chemical stockpiles in Egypt (possible, albeit possibly small or old), Israel (a total unknown), and North Korea (unknown but possibly quite large). None have made declarations to the OPCW. One can envisage a wide variety of geopolitical scenarios in which demilitarisation efforts for newly-declared or discovered chemical stockpiles may be relevant. Chemical demilitarisation has slowed down considerably, but it is by no means irrelevant.

Dan Kaszeta