Why allegations of chemical weapons use are hard to investigate

The White House has warned Russia could use unsupported claims about biological and chemical weapons development in Ukraine as cover for escalating the war there, underscoring the power — and limits — of chemical and biological forensics.

The big picture: Allegations that chemical or biological weapons have been used can be difficult to investigate and are one way for a country to create a pretext for aggression.

• Tying a chemical or pathogen to a source and attributing it to an actor can be a long, tedious process that doesn't necessarily produce definitive answers.

Background: Chemical weapons use toxic agents (for example, sarin, chlorine and mustard gas) to poison or injure people and tend to have quick, localized effects.

• Bioweapons involve releasing dangerous viruses (like smallpox) that can spread in a population or bacteria such as anthrax.
• Signatories of the Chemical Weapons Convention — including the U.S. and Russia, which both declared having stockpiles, and Ukraine — have agreed to destroy any chemical weapons they possess. Russia says it has complied (but Kremlin critics have since been poisoned with Novichok nerve agents). The U.S. has a deadline of Sept. 30, 2023, to destroy the 715 tons of chemical weapons it still possesses.
• Biological weapons are banned under the 1972 Biological Weapons Convention (BWC).

How it works: A suspected or alleged chemical attack or incident can be investigated by the Organization for the Prohibition of Chemical Weapons (OPCW) or, for biological weapons, by the UN Secretary General or through countries that are part of the BWC.

• Investigations consider an array of evidence, including analyses of samples from the site (which can be difficult to access), interviews with witnesses, and collecting and deciphering epidemiological data as well as more traditional forensics of munition fragments, fingerprints, fuses and other traces of the incident.
• Confirming a chemical or biological agent was used at a location or determining how it was made relies on standard tools in chemistry and biology: DNA and RNA sequencing and microscopy for analyzing biological samples; mass spectrometry, gas chromatography, NMR and others for chemical forensics.

A signature of a pathogen's source is its genetic sequence, which can have different patterns compared to other samples of the same microbe, because of recombination and mutations.

• In chemicals, the constituent atoms don't vary from one molecule to the next. But impurities, additives, byproducts or other "gunk and junk," as Dan Kaszeta, who has worked in chemical and biological defense for the U.S. Army and other agencies, describes it, can indicate how and where a chemical agent was made.
• Byproducts and the additive hexamine linked a sarin attack in the Syrian town of Khan Sheikhoun in 2017 to the Assad government, according to a OPCW-UN report. Syria and Russia, which supports Assad's forces, deny chemical weapons were used and blame insurgents.

Yes, but: Determining who used a chemical or biological agent "tends to be much more complicated than just the chemistry or biology," Kaszeta says.

• In Syria, the probative information was hexamine in the sarin but the smoking gun was a document in which the Syrian government, when it joined the OPCW in 2013, declared hexamine as part of their chemical inventory, he says.

• In the 2001 anthrax attacks in the U.S., the spore samples in letters sent to victims were, after six years, matched to a batch of a particular anthrax strain accessible to only a few people, a breakthrough that helped narrow the suspects and ultimately identify Bruce Ivins as the mailer.

What to watch: Gregory Koblentz, director of the Biodefense Graduate Program at George Mason University, says that, rather than use a chemical or biological weapon for an attack in Ukraine, there is a risk "Russia will invent or stage an event, claim it as an atrocity and use it domestically for escalating their commitment to the conflict."

• "Even if the U.S. and Ukrainians could expose this was staged or a hoax, on some level, the disinformation would be out there, and some would throw up their hands and say they don't know and are going to sit it out," he says.
• Another concern for Koblentz is that unsubstantiated claims that bioweapons are being developed in Ukrainian labs that study and surveil pathogens like Crimean hemorrhagic fever could damage international cooperation on biosecurity and pathogen surveillance among labs around the world.

What's next: The BCW is scheduled to meet in August to discuss how its mechanisms for resolving concerns about biological weapons compliance could be strengthened.

• There had been signs over the past few years that parties may be willing to agree to measures that would facilitate verifying whether parties are complying. But "now there is no way it will be a constructive diplomatic event," Koblentz says. "It's been sacrificed for geopolitics."