Briefing Note: Update on the Salisbury poisonings

The following briefing note is developed by academics researching the use of chemical and biological weapons during the 2011-present war in Syria. The note reflects work in progress. However, the substantive questions raised need answering, especially given the seriousness of the political situation in the Middle East and UK-Russian relations. The authors welcome comments and corrections.

Authors: Professor Paul McKeigue (University of Edinburgh), Professor David Miller (University of Bath) and Professor Piers Robinson (University of Sheffield)

For correspondence: ; Working Group on Syria, Media and Propaganda (

Key points

  • The Skripals were exposed to a phosphoroamidofluoridate compound named A-234, of high purity indicating that it was most likely prepared for research purposes.
  • A-234 or similar compounds have been synthesized at bench scale by national chemical defence labs in Russia and the US in the 1990s, and more recently in Iran and Czechia. A small quantity of A-234 from a Russian state lab was used in the murder of Ivan Kivelidi and Zara Ismailova in 1995.
  • No data on the toxicity of A-234 are available in the public domain. The police statement that the Skripals were exposed through contact with their front door is implausible as there are no known nerve agents that cause onset of symptoms delayed by several hours, and it is improbable that absorption through the skin would cause both individuals to collapse later at exactly the same time.
  • Although Russia is one of several countries that have synthesized A-234 or similar compounds, there is no evidence other than Vil Mirzayanov’s story that these compounds were ever developed (implying industrial-scale production and testing of munitions) for military use. Mirzayanov’s credibility as an independent whistleblower is undermined by his role in a Tatar separatist movement during 2008-2009, backed by the US State Department.
  • There are multiple indications that the UK is hiding information:-
    • the withholding of the identity of the compound as A-234. For example, the UK statement to the OSCE12 April 2018 states only that ‘ the name and structure of that identified toxic chemical is contained in the fall classified report to States Parties’. See also this briefing. The Chief Executive of Porton Down, in his statement 3 April,referred to the compound only as ‘Novichok’.
    • the withholding of information about its toxicity
    • the issue of a Defence Media Security Advisory notice on the identity of Skripal’s   MI6 handler and the attempt to conceal or deny his role in Orbis Business Intelligence.
    • the sequestration of Yulia Skripal.
  • The UK government’s case against Russia, stated in a letter to NATO, is based on asserting that “only Russia has the technical means, operational experience and motive for the attack on the Skripals”. Each of these points is open to question:-
    • Technical means: it is not seriously disputed that compounds such as A-234 can be produced at bench scale in any modern chemistry lab.
    • Operational experience: it is alleged that Russia has a track record of state-sponsored assassination, but this is not enough to support the assertion that “only Russia” could have enough experience to attempt unsuccessfully to assassinate two unprotected individuals.
    • Motive: No other attempted assassinations of defectors from Russian intelligence services have been recorded. Even if such an assassination campaign had been ordered, the Russian state would have good reasons not to initiate it in the first half of 2018.   In contrast there are obvious possible motives (outlined below) for other actors to have taken steps to silence Sergei Skripal at this time.

What was the agent used?

An early report that the hospital was dealing with poisoning caused by an opiate such as fentanyl was most likely based on the initial working diagnosis. Signs of organophosphate poisoning – constricted pupils, vomiting, reduced consciousness and reduced breathing – could easily be mistaken for opiate overdose, usually a more likely diagnosis.   OPCW has stated that the BZ detected by the Swiss Federal Institute for Nuclear, Biological and Chemical Protection in one of the samples sent by OPCW was not from Salisbury but was in a control sample.

The Russian ambassador reported that on 12 March the Foreign Secretary had told him that the nerve agent used against Mr and Ms Skripal had been identified as A-234.   The OPCW report issued on 12 April did not identify the agent but stated that they had confirmed the identification made by the UK and that this identification had been included in the confidential report provided to “States parties”. On 14 April the Russian Foreign Minister stated that A-234 had been reported by the Swiss Federal Institute for Nuclear, Biological and Chemical Protection that was one of the four accredited labs used by OPCW to analyse the Salisbury samples.

Based on public reports, a ChemSpider record for A-234 has been created which assigns it the IUPAC name ethyl [(1E)-1-(diethylamino)ethylidene] phosphoramidofluoridate. Its predicted vapour pressure is very low indicating that it is predicted to be non-volatile. No information on its stability is available.   The OPCW director Uzumcu stated in a newspaper interview that the agent “seems to be very persistent,” and “not affected by weather conditions”. This was confirmed the next day by an OPCW press statement that: “the chemical substance found was of high purity, persistent and resistant to weather conditions”. Ian Boyd, the chief scientific adviser at the Department for Environment, Food and Rural Affairs, was reported to have stated: “The chemical does not degrade quickly. You can assume it is not much different now from the day it was distributed”.   No experimental studies of the stability of A-234 have been reported.

Who could have produced A-234 in bench-scale quantities?

It is no longer seriously disputed that, as noted in our earlier briefing, any well equipped university lab can synthesize and purify such chemicals at bench scale. OPCW reported that the agent (presumably A-234) was of high purity with “almost complete absence of impurities”.   This suggests that it was from a batch that had been synthesized for research, rather than for assassination purposes where it would be unnecessary to purify the agent.

Uzumcu stated in an interview with the New York Times that he had been told by UK officials that 50-100 grams of the agent was used.

“For research activities or protection you would need, for instance, five to 10 grams or so, but even in Salisbury it looks like they may have used more than that. Without knowing the exact quantity, I am told it may be 50, 100 grams or so, which goes beyond research activities for protection”

OPCW quickly contradicted this in a statement that “OPCW would not be able to estimate or determine the amount of the nerve agent that was used in Salisbury on 4 March 2018. The quantity should probably be characterized in milligrams”.

Who has studied A-234 or similar compounds?

Bench-scale research on the toxicity of agents that might be used in chemical warfare is entirely legitimate under the Chemical Weapons Convention, and does not have to be declared to OPCW.


Since our last briefing note, more material from the investigation of the Kivelidi poisoning has been published by Novaya Gazeta, updating the earlier article published on 22 March. The second article includes an image of the mass spectrometry profile of the sample recovered from the telephone handset, which matches that submitted by Edgewood to the NIST98 mass spectrometry database. The Russian experts who commented on the original result appear not to have had access to the mass spectrometry profile of A-234, and to have incorrectly reconstructed the structure from a best guess, based on the mass-charge ratios of the fragments, as something like the GV agent (both agents have molecular mass 224 daltons, and a 58-dalton fragment).   This establishes that Russia had synthesized this compound at bench scale by the mid 1990s, but does not confirm that it was ever developed for military use as alleged by Mirzayanov.


A 1997 newspaper article refers to a secret US army intelligence report referring to Russian development of A-232 and its “ethyl analog” A-234, indicating that the designation of these compounds and their structures was known to the US by this time. As noted in our last briefing note, the Edgewood lab submitted a mass spectrometry profile for A-234 to the public database NIST98, which was current from 1998 to 2001.

A patent application submitted by a US government lab in 2008 mentions “Novichoks”, but examination shows that the structures given for these compounds were the dihaloformaldoxime structures previously published as supposed “Novichoks”, not the phosphoramidofluoridates published by Mirzayanov later in 2008.   This does not indicate that the applicants were studying these compounds – most likely they included them to make their patent as broad as possible.

Iran and Czechia

A study from Iran published in 2016 reported synthesis for research purposes of a compound similar to A-234, differing from it only by the presence of methyl instead of ethyl groups. In an interview with Czech television, President Zeman stated that in November 2017 the related compound designated A-230 was studied at the Brno Military Research Institute.

Other labs

The director of Porton Down has declined to comment on whether Porton Down has stocks of A-234 for research purposes. The OPCW labs that identified A-234 in the specimens from Salisbury were most likely matching it against a mass spectrometry profile in OPCW’s Central Analytical Database.

What is known of the toxicity of A-234?

No data on the toxicity of A-234 are available in the public domain. The printout of the entry in the NIST 98 database appears to cross-reference an entry in the database RTECS (Registry of Toxic Effects of Chemical Substances) but no entry for this compound now exists in RTECS.

Why was the structure of A-234 revealed?

The structure of A-234 was revealed in a book by Vil S Mirzayanov in 2008, some 13 years after he had emigrated to the US with the story of a secret programme to develop chemical weapons of a class named “Novichoks”. During 2008-2009 the US government, with an active part for the Secretary of State Hillary Clinton, was encouraging the development of a separatist movement in Tatarstan. As part of this, Mirzayanov was declared head of a Tatar government-in-exile in December 2008.   The publication of his book may thus have been part of an effort to build up Mirzayanov’s status as a dissident. His role in this operation may explain why subsequent discussion of his book by OPCW delegates was closely monitored (and discouraged) by the US State Department.   Mirzayanov’s involvement in this operation undermines his credibility as an independent whistleblower.

When and where were the Skripals exposed to A-234?

A summary of the different versions on which journalists were apparently briefed by security sources was given by the Russian embassy:-

– The Skripals could be sprayed with poison by attackers in the street (Daily Mail, 6 March, source: “Anti-terror police”).

– The nerve agent could be planted in one of the personal items in Yulia Skripal’s suitcase before she left Moscow for London. According to this theory the toxin was impregnated in an item of clothing or cosmetics or else in a gift that was opened in the house of Sergei Skripal in Salisbury, meaning Yulia Skripal was deliberately targeted to get at her father (The Telegraph, 15 March, source: “Senior sources in the intelligence agencies”).

– The nerve agent could be planted in the air conditioner of the car of Skripals (Daily Mail, 19 March, source: “Security expert Philip Ingram”).

– The Skripals could be poisoned through buckwheat that Yulia Skripal had asked her friend to buy and bring for her father, because she had forgotten to pick up the grocery gifts herself (The Sun, 1 April, source: “British investigators”).

On 28 March the police announced that “at this point in our investigation, we believe the Skripals first came into contact with the nerve agent from their front door”.

Although it is possible that a nerve agent could be prepared in a formulation that would be absorbed only slowly through the skin, it is implausible that two individuals exposed through contact with the front door would have received doses that caused them to collapse suddenly and so nearly simultaneously that neither had time to call for help, at least three hours later.   It is more likely that they were attacked shortly before they were found collapsed on the park bench.

Sergei Skripal’s link with Orbis: possible motive for murder

In the first few days after the poisoning there were media reports that Sergei Skripal had been in regular contact with his MI6 handler, whose Linked-In profile had stated that he was a consultant for Orbis Business Intelligence. On 7 March this profile was deleted and a Defence and Security Media Advisory Notice was issued to caution journalists against disclosing the identity of this consultant. However at Skripal’s trial in 2007 his MI6 handler had been identified as Pablo Miller, and the link between Skripal and Miller had been described in detail by Russian opposition media on 6 March.

This link between Skripal and Orbis may be relevant to the dossier compiled by Christopher Steele, the founder of Orbis, containing derogatory information on Donald Trump’s alleged ties to Russia. This dossier had been used by the FBI to apply for a Foreign Intelligence Surveillance Act court order authorizing surveillance of Trump’s campaign. By early 2018 the unravelling of this story was creating serious difficulties for Steele and for those he had worked with. These difficulties included a referral for criminal investigation by two US Senators, a libel case in the US against the publisher of the dossier which had led to a court ruling that Steele should be questioned in an English court, and a libel case in England against Orbis and Steele.   It is not difficult to postulate a situation in which the potential for damage to US-UK relations could have provided a motive for actors on both sides of the Atlantic to ensure that Sergei Skripal would not be available to give evidence.

The UK government’s position

This was summarized in a letter from the National Security Adviser, Sir Mark Sedwill to the NATO Secretary-General on 13 April 2018.   Sedwill’s letter made several assertions that were substantiated only by “intelligence”:

  • By 1993, when Russia signed the Chemical Weapons Convention, it is likely that some Novichoks had passed acceptance testing, allowing their use by the Russian military
  • Russia further developed some Novichoks after ratifying the convention
  • During the 2000s, Russia commenced a programme to test means of delivering chemical warfare agents and to train personnel from special units in the use of these weapons. This programme subsequently included investigation of ways of delivering nerve agents, including by application to door handles.
  • In the mid-2000s, President Putin was closely involved in the Russian chemical weapons programme
  • Within the last decade Russia has produced and stockpiled small quantities of Novichoks

Appearing before the House of Commons Defence Committee on 1 May, Sedwill (11:39) extolled the government’s reaction to the Salisbury incident as “an example of the Fusion Doctrine in practice”. The Fusion Doctrine brings other government departments under the National Security Council with “the introduction of senior officials as senior responsible owners to deliver each of the NSC’s priorities”.

Sedwill’s involvement in the preparation of the now widely discredited dossier ‘Iraq’s Weapons of Mass Destruction, released in September 2002, calls into question his credibility in making these uncorroborated assertions.   The UK government’s case as set out by Sedwill is based on asserting that “only Russia has the technical means, operational experience and motive for the attack on the Skripals”. Each of these points is open to serious criticism:-

  • Technical means: it is not seriously disputed that A-234 can be produced at bench scale in any organic chemistry lab.
  • Operational experience: it is alleged that Russia has a track record of state-sponsored assassination, but this does not support the assertion that only Russia has the operational experience for such an assassination. On the contrary, the failure of the assassination attempt, against two unprotected individuals, suggests that the perpetrators lacked the operational experience and competence that one would expect of state-directed assassins.
  • Motive: no other attempted assassinations of defectors from Russian intelligence services have been recorded. If the Russian state had decided to begin assassinating these defectors, it is unlikely that they would have chosen to start in March 2018, just before the presidential election and three months before the FIFA World Cup.   However, as noted above, it is possible to identify motives for other actors to silence Sergei Skripal at this time.


We thank Professor Rudy Richardson of the University of Michigan for advice on the toxicology of nerve agents.


This entry was posted in chemical weapons, guest blog, OPCW, Russia, UK Government, Uncategorized, war. Bookmark the permalink.

17 Responses to Briefing Note: Update on the Salisbury poisonings

  1. nicolaavery says:

    Reblogged this on fighting stuff.

    • LittleOldMe says:

      Awesome journalism. The kind we sourly lack in the msm. But I guess they are all “bought and paid for”… This whole story has looked like a farce from the start, especially in the msm. Like they were making it up while they were going along… Sounded like: ( Who do exactly that sort of thing.

      My question is: Is it even likely that two people will touch the same door handle, either on their way in or out of the house? Two people and two door handles (inside and outside).

      When you leave together, only ONE person will touch the outside door handle, when closing the door, usually the last one to leave, right?

      Just my 2 cents 😀

  2. Brendan says:

    The authors say ” there are no known nerve agents that cause onset of symptoms delayed by several hours, …”

    A publication from 2009 contradicts this, but it seems to suggest that the onset is gradual rather than sudden:

    “Even a lethal drop may require 30 minutes, rather than seconds, to manifest clinically, and a small, nonlethal drop may develop symptoms over 18 hours.”
    “Nerve Agents”, Jonathan Newmark, in Clinical Neurotoxicology

    This delayed reaction still does not explain the unbelievable timeline of the symptoms in the official British version of the Skripal case. As the authors point out, that version is unlikely to be true, as it would mean that the two victims collapsed suddenly and almost simultaneously after a long delay.

    It is all the more unlikely, as Yulia should have collapsed later than Sergei, due to the difference in the skin layers in men and women. Because the subcutaneous layer is thicker in women, the nerve agent’s transit time is longer, according to Newmark’s piece.

    • Brendan says:

      Those comments by Newmark refer to absorbtion of nerve agent through the skin. This is in contrast to what he says about inhalation of a large amount of vapour:

      “In a vapor challenge of sufficient magnitude, perhaps 0.5 LCt50 or higher, the sequence of symptoms can be so fast as to seem clinically simultaneous. Many patients have been described who, after a large vapor challenge, lost consciousness, seized, and developed all of the other symptoms essentially within seconds of exposure.”

      This sudden attack due to vapour appears very consistent with the Skripals’ inability to call for help when they collapsed.

      Furthermore, for more than three weeks after the incident, the only methods of poisoning that were taken seriously involved the inhalation of nerve agent. First, it was supposed to have been sprayed on the Skripals in the park. Later, it was believed that Novichok in powder form had been placed in the ventilation system of Sergei’s car.

    • Brendan says:

      As well as the rapid onset of symptoms of vapour inhalation, Newmark also describes its possible long term effects, which he contrasts with those resulting from skin contact:

      “Vapor nerve casualties, if removed from the source of contamination, or masked, and treated aggressively, either die or improve rapidly. Humans metabolize a circulating nerve agent quickly if it does not kill them. No depot effect is observed with vapor casualties. The situation is quite different with the patient who gets a drop of liquid nerve agent on the skin.”

      The most important part of that section is “Vapor nerve casualties … either die or improve rapidly.” This is consistent with the prognosis for the Skripals both before and after their recovery.

      For three weeks, Sergei and Yulia were given little chance of recovery. On Monday 26 March, Prime Minister Theresa May told Parliament “Sadly, late last week doctors indicated that their condition is unlikely to change in the near future and that they may never recover fully.”

      In the two days after that, others – who were close to the Skripals – put it more bluntly.
      Viktoria Skripal, who is Sergei’s niece and Yulia’s cousin, told the BBC that there was “maybe 1 percent of hope” and that they had “a very small chance of survival”.

      Ross Cassidy, a close friend and former neighbour of Sergei, told Sky News: “We’ve already been told they will be severely mentally impaired and I don’t think they would want that. I think death would probably be merciful.”

      Then on 29 March, Salisbury District Hospital unexpectedly said that “Yulia Skripal is improving rapidly and is no longer in a critical condition.” She was even “conscious and talking” at that stage, according to the BBC.

      A few days later, she was able to phone Viktoria, who said she sounded perfectedly normal, and a few days after that, Yulia was discharged from hospital. Around that time too, the hospital announced that Sergei’s condition also improved rapidly.

      All of this indicates a much greater likelihood that Yulia and Sergei were poisoned by means of inhalation than skin contact. Not only that, but the doctors treating them, and the UK authorities, must have believed that too.

    • Brendan says:

      Bizarrely, however, one day before Yulia’s rapid recovery was announced, the British police presented a new version of events which begins with skin contact. This is the door handle story, where the Skripals first made contact with Novichok at the front door of Sergei’s house.

      This version gives the impression that the investigators had not noticed the Novichok on the front door during the weeks of intensive investigation by hundreds of officers! This is in spite of the fact that it was known that their colleague, Detective Nick Bailey, had been to the house before he suffered from the effects of the nerve agent.

      The unexpected announcements of both the door handle story and Yulia’s rapid recovery within a day of one another, three weeks after the incident, appears to be a remarkable coincidence in timing.

      It reminds us of another such example that was already mentioned – the Skripals’ collapse at almost the same time, hours after touching the Novichok. That’s part of the same unbelievable door handle theory.

      This is just speculation, but the timing of the shift in narrative indicates that the UK authorities were afraid of what Yulia might reveal. Now that she was “conscious and talking”, she might even be able to help to identify the attackers.

      Because of this, they may have wanted to discredit what she might say about what she noticed in the centre of Salisbury on the day of the poisoning. By moving the crime scene to Sergei’s house, the police could dismiss any such statements by Yulia as irrelevant, or maybe as the result of hallucination caused by the nerve agent.

    • Brendan says:

      Just a summary of some facts about the Skripal case that might point to the means of poisoning. These all indicate that it was not by skin contact, but much more likely by inhalation, or possibly ingestion. The first two facts match what the literature says about nerve agent vapour:

      – Rapid (instead of gradual) onset of the poison’s effects in both victims at the same time.

      – Grim prognosis, followed by rapid improvement (“Vapor nerve casualties … either die or improve rapidly”).

      – The investigators’ belief for weeks that the poison was either in aerosol or powder form or was added to food. (we can see these scenarios both in the leaks to the media and in the focus of investigation in Salisbury town centre).

      – In contrast, the apparent complete lack of belief for weeks in the door handle theory, which involves skin contact.

      – The strange timing of the first mention of this version. It was presented – almost as a fact – after three and a half weeks of intensive investigation, approximately on the day of Yulia’s unexpected recovery.

  3. Neil says:

    This breifing proceeds on the premise that the Skripal’s were exposed to A-234. I can not see that this has been established beyond reasonable doubt. If the information referred to by Segei Lavrov is reliable, it must pertain to environmental samples and not biomedical samples. Presumably A-234 is a fast acting nerve paralysing agent, it would therefore seem incongrous that the Skripals could have had any significant exposure to it but be recovering fully (apparently). Not least if they were exposed to it and then initially assessed and treated for fentanyl exposure.

  4. Pingback: The Salisbury Poisonings. What Was the Agent Used? Who Could Have Produced It? When and Where were the Skripals Exposed? |

  5. And how prescient of the MD of UK CBRN respirator-maker, Avon Protection, to write a piece on the BBC pretty much predicting a chemical attack on a NATO member, possibly involving ‘new super chemicals many times more potent than nerve agents like Sarin and VX’, just days before the Salisbury incident

  6. Brendan says:

    The latest story is that the Kremlin targeted Sergei Skripal because he travelled to Prague and Estonia in order to provide security officers with information on Russian espionage.

    But wait … isn’t Estonia the place where another Salisbury resident, Skripal’s alleged handler, Pablo Miller was based for years as an MI6 agent?

    And wasn’t Prague the location of a meeting between Trump’s lawyer Michael Cohen and Russian officials, as alleged in the Steele Dossier?

    And wasn’t that meeting – just a couple of months after Skripal’s trip to Estonia in 2016 – monitored by the Estonian secret service, according to Newsweek?

    And hasn’t it been suggested in many places, including the article above, that Skripal’s apparent connection with the Steele Dossier could be a motive for some western spooks to want to silence him?

    So the revelation of Sergei Skripal’s trips to Prague and Estonia actually supports the evidence for his connection with the dossier. However, they have been presented in the media as the opposite – as a motive for the Kremlin to try to kill him.

    These latest media reports smell a lot like damage limitation. What do you do if you cannot stop an embarrassing fact from being revealed? The best action is to spin it to completely change its significance, so that it shifts the blame onto your enemy.

  7. Adrian Kent. says:

    HI Tim,

    Full marks for your work here – are there any updates coming in the light of recent events?

    The way you’ve gone about this is particularly impressive and useful – posing questions and answering them as and when you can.

    This stands in rather stark contrast to a few of the more prominent ‘company-liners’ on twitter.

    I’ve had a diverting, but not entirely fruitful, few exchanges with @dankaszeta on the subject of Novichok persistence and the delayed, simultaneous, rapid onset story (to my mind the most obvious flaw in the Governments yarn). In April he was happy enough to state that all OP chemicals degrade in the presence of water as it suited him in his, ahem, Myth Busting piece for

    Now, however, it’s all actually rather persistent and down to viscosity and all that. I fully understand how it might be were it enclosed in a vial or syringe or something, but it all looked a bit like he was having his cake and eating it when he’d used the hydrolysis argument to explain why the Skripals weren’t killed (or why, I assume PC Bailey wasn’t either).

    Philip Ingrm (@PhilipIngMBE) chimed in on a recent thread – informing me that the persistence was why they (I’m assuming he meant the Russians) decided to use Novichoks. When it came to the delayed collapse story he told me that this was answered in his, Kaszeta’s or Hamish DBG’s threads. It’s a tactic that certainly Kaszeta has deployed more than once – feign weariness when questions get tricky and then refer people to tweets they’re too busy or tired to dig out themselves. I told Ingram that I thought this was a little lame and pointed him to this site by way of example of good practice.

    The upshot?

    Dan Kaszeta blocked me.

  8. Pingback: FFWN: 2019 New Years special: biggest stories of 2018 – Kevin Barrett

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