Oct 7, 2013

Prior Alleged Chemical Attacks

If this is your first time here, I recommend starting from the conclusion page.

A common claim made for the regime attack theory is that it was just one of many chemical attacks. For example, the UK Intelligence assessment claims lethal chemical weapons were used in 14 occasions. If indeed the regime has used chemical weapons in the past, it would constitute very strong circumstantial evidence for its culpability in the August 21st attack. To evaluate the strength of such evidence, I analyze in this post the reports of previous chemical attacks.

A major limitation in examining these reports is the high motivation among the opposition to convince the world that chemical weapons are used by the regime. From the moment Obama issued his red line in August 2012, and especially after his direct threat on December 4th, 2012 ("if you make the tragic mistake of using these weapons, there will be consequences"), the opposition started frequently giving erroneous reports of chemical attacks. For example, in this video  a doctor shows a chemical detection kit and describes it as a chemical weapon captured by the FSA (similar examples here). In this video from one week after the red line speech, Syrian Surface-to-Air missiles seized by rebels are reported to be chemical missiles (minute 1:56). More examples are described below and many more can be found online.

This is further complicated by the fact that many nerve agent symptoms may be caused by other types of injuries (e.g. foaming), or by common medical treatments (e.g. morphine causes miosis), and can also be easily faked. Even sarin blood and urine tests can be faked by drinking diisopropyl methylphosphonate, a chemical available on the market (see the comments for details).

One thing that becomes clear when reviewing videos from claimed chemical attacks is the large number of incidents in which victims show symptoms that seem to be caused by a strong irritant.

Differentiating between an irritant and a nerve agent is not difficult. Nerve agents affect the nervous system and cause loss of control of the body. Victims will often appear calm or sedated and report mild symptoms such as loss of vision, dizziness, and nausea, while the more advanced symptoms such as convulsions and foaming are normally accompanied by loss of consciousness. The progression of symptoms is generally rapid and painless.
Irritants, on the other hand, cause damage to sensitive organs, resulting in aggressive conscious responses such as forceful coughing, vomiting, and noticeable suffering.

To explain this inconsistency in symptoms, it is often suggested that a combination of sarin with a weaker agent has been used, in an attempt to create some less-than-lethal weapon. As described in detail in Brown Moses’ interviews with chemical experts this is highly unlikely: Sarin is designed to kill, and has no other effective use. It is also chemically unstable and should be kept away from other chemicals.

Keeping this in mind, let’s analyze the reports one by one:

Daraya 6-Dec-2012

This is the first claim of a chemical attack, made 2 days after Obama’s direct threat (if anyone has an earlier report, please share).
According to this report “the regime forces shelled Mohasan and Buomar by Phosphorous Bombs and threw toxic gases in Daraya”.
There are no videos from Darayya claiming a chemical attack, but there were definitely clashes going on at the time. There are videos that clearly show a White Phosphorus attack in Mohasan.

Conclusion: No evidence of a chemical attack. Possibly White Phosphorus.

Aleppo 8-Dec-2012

A video showing burn victims claimed to be from a regime chemical attack.
Nerve agents do not cause burns of this level, leaving us with the option of mustard gas (the only chemical weapon in the Syrian arsenal that is not a nerve agent). At high concentrations Mustard gas would cause severe respiratory problems, which are not present here. At lower concentrations blisters would develop over a few days, causing severe pain.

Conclusion: No evidence of a chemical attack. Probably misrepresentation of the cause of injuries.

Darayya 22-Dec-2012

The regime reports losing 7 soldiers to a rebel attack with a yellow toxic gas. No evidence is presented.

Conclusion: Unverifiable

Homs 23-Dec-2012

This is the first of many attacks that are documented by video and seem to show similar symptoms, including severe respiratory irritation, vomiting, and pain. The agent is described as a “white smoke”.

This video (minute 1:14) and this video (minute 1:08) seem to show normal sized pupils.  
While it is theoretically possible to be exposed to nerve agents without suffering miosis, this seems to be very rare in practice: 99% of victims of the sarin attack in Tokyo exhibited miosis.

Some speculated that Agent 15was used in this attack, but the symptoms seem highly inconsistent.

Victims are all males of fighting age.

Conclusion: Irritant used on a military target, possibly White Phosphorus. 7 reported dead, but no evidence this was the cause.

Khan Al Assal 19-Mar-2013

This attack is very different from the other attacks described here, in several aspects.

Following this attack, the Syrian government requested a UN investigation. This was delayed following requests by Western governments to allow the UN team to visit other sites, which was initially refused by Syria. During the negotiations, Russia sent its own investigation team which found traces of sarin and blamed the opposition. Of course, the area is under control of the Syrian Army and the investigation was done by a Syrian ally, damaging the reliability of this report. 

An agreement was eventually reached as to which sites could be visited, and the UN team was sent to Syria. However, upon its arrival the August 21st attack took place, and the team was diverted there. On September 25th they returned to complete the investigation.

This attack is also far deadlier than all others, with 26 deaths compared to none or low numbers in other attacks. It is also the only one with civilian casualties.

Videos from the attack are available but seem to have been taken a long time after it occured. This video shows one victim foaming at the nose. In this video symptoms are reported to include “immediate fainting, convulsion and death”, which are consistent with nerve agents and not with irritants.

The victims seem to be a mix of Syrian soldiers and regime-supporting civilians (One blames ‘terrorists’ for the attack, and another is wearing the official Syrian flag on her hand). An opposition source blamed the attack on the regime, claiming it was a false-flag attack on the regime-supporting town.

Some eyewitnesses report smelling chlorine, which is a simple chemical weapon to deploy, and was used numerous times by Iraqi insurgents. However, the symptoms reported (convulsions, immediate fainting) are inconsistent with chlorine, and chlorine symptoms like skin or eye irritations were not reported. The chlorine smell could theoretically be the result of low-budget sarin production, but in that case many other smells should have been reported.

Conclusion: Seems like a lethal chemical attack, possibly sarin, possibly chlorine. Not enough evidence to determine culpability, but a rebel attack seems much more likely.

Otaybah 19-Mar-2013

Three videos from this event: One showing an unconscious victim foaming at nose, another showing victims with no specific symptoms, and another showing two bodies claimed to have been killed by a chemical attack. All are males of fighting age.

Conclusion: Not enough evidence.

Adra and/or Douma 24-Mar-2013

According to the Le monde article 39 people were affected and two died.

This video shows mild convulsions, and its title describes “chemical and phosphorus weapons". Another video showsbloody discharge from the nose. While nerve agents can cause bleeding from mouth and nose, this seems to be rare and all records of foaming from Zamalka mentioned white foam.

Victims are males of fighting age.

Conclusion: Not enough evidence. Possibly white phosphorus

Jobar 7-Apr-2013

One video found claiming sarin or VX, while showing a victim coughing violently, and describing nine victims fainting, losing eyesight, and coughing severely. Another victim has miosis and is filmed from three different angles and lighting conditions, possibly in an attempt to look like multiple victims. Since he is not exhibiting any other symptoms, this seems very dodgy.

Conclusion: Probably an Irritant misrepresented as nerve agent.

Jobar 12-14 Apr 2013

This event was not documented but it is reported as one of two events for which the French government received blood samples that tested positive for sarin.
This is probably related to an event described in the Le Monde article:
On April 13, the day of a chemical attack on a zone of the Jobar front, Le Monde's photographer was with rebels who have been waging war out of ruined buildings. He saw them start to cough before donning their gas masks, apparently without haste although in fact they were already exposed. Men crouched down, gasping for breath and vomiting. 
These symptoms suggest the use of an irritant rather than a nerve agent, and the article gives no explanation why a professional photographer did not document an event of such importance (adding to many other inconsistencies in the Le Monde article which I’ll hopefully get to in the future). It therefore seems there is no way to know the source of these samples.

Conclusion: Unverifiable. Possibly irritant, possibly sarin.

Sheikh Maqsoud (near Aleppo) 13-Apr-13 and Saraqeb 29-Apr-13

These two attacks were analyzed by Brown Moses here, here, and here. Both attacks used the same small white canisters, and in Saraqeb a helicopter is seen dropping something that leaves a trail resembling that of White Phosphorus.

Symptoms shown in videos include severe coughing, vomiting, miosis, foaming and convulsions.

Samples from 13 Saraqeb victims were taken to turkey and tested negative for sarin. France, on the other hand, reported finding sarin in samples from Saraqeb and Jobar (13-Apr-2013, see above). The manner in which the samples were taken is unclear.

Following the Saraqeb incident, the regime accused the opposition of carrying two false-flag chemical attacks in the town. One in which powder was thrown on civilians, and another in which they brought hostages to a site of a chemical accident. No evidence was provided for either claim.

Conclusion: Contradicting evidence makes these events difficult to figure out, but the evidence for sarin seems weak.

Barzeh 26-Apr-13

The regime reported that Syrian troops were attacked by a chemical shell. The symptoms mentioned include asphyxia, nausea, foaming of mouth and nose, loss of consciousness and indirect contamination of medical personnel. Of all cases examined here, this is the only report where many sarin symptoms are described accurately. Of course, all we have is the news reports and no evidence.

Conclusion: Unverifiable.

Qasr Abu Samra (near Homs) 14-May-2013

According to this article, this is one of four instances in which the US believes chemical weapons were used. I could not find any evidence of such an attack.

Conclusion: Unverifiable.

Adra (patients treated in Douma) 23/24-May-2013

This incident has a large number of videos, which show unconscious victims, one case of convulsions, one case of miosis (also seen here), another case of foaming at the mouth, another case of disorientation accompanied by miosis. Other victims do not present miosis, which as mentioned above is atypical to nerve agent exposure.

This incident is unique in that in one of the locations medical personnel are treating patients while wearing gas masks. Something that was not seen in any other video, including Douma videos from the August 21st attack.

All victims are males of fighting age.

Conclusion: Unclear. These are the only videos showing significant symptoms consistent with nerve agent exposure. However, not enough evidence is available to determine this is indeed the case.

Harasta 26-May-2013

This video seems to have been taken a significant time after the attack, with no atmosphere of emergency. The doctors report treating 200 people with symptoms of vomiting and dizziness. Since (a) vomiting is an advanced symptom of sarin accompanied by other symptoms that are not reported, (b) few deaths were reported, and (c) no second-hand contamination to medical personnel is reported, this does not seem to be a sarin attack.
An earlier video shows one victimg shivering and in pain, and another shows several victims with no specific symptoms.

All victims are males of fighting age, some wearing military vests.  

Conclusion: Unclear. Symptoms seem to go beyond those of the other irritant cases, but are still not consistent with a nerve agent. Perhaps some strong riot control agent?

Al-Otaybah 26-May-2013

This video shows a doctor describing symptoms of miosis and convulsions. He shows blood samples which are to be sent for analysis to prove the use of chemical weapons, and then mistakenly describes a chemical detection kit as a chemical weapon.

Conclusion: No evidence of a chemical attack.

Jobar 27-May-2013

This video shows several males of fighting age suffering from respiratory irritation, with the cameraman claiming sarin was used.
A civilian girl is shown breathing heavily, but does not show other symptoms.

Conclusion: Possible irritant use.

Zamalka 19-Jun-2013

Reported here. One video found, showing a victim with bloody foam  – somewhat similar to a symptom seen in the 24-Mar-2013 attack, and not typical to nerve agent exposure.

Conclusion: Unclear. Probably not a nerve agent.

Adra and Douma 5-Aug-2013

These two attacks were already analyzed hereMore videos can be seen here and here, with a victim describing a “red color”, “sulfur smell”, blurred vision, and suffocation.

While the Adra victims are males of fighting age, exhibiting similar symptoms to other attacks, the Douma incident seems to be of a much wider scale and involving many civilians, although with light injuries and no deaths.

Conclusion: Adra seems like a typical irritant attack on opposition forces. Douma could be White Phosphorus smoke from a fighting zone reaching a civilian area.

Summary of Findings
  1. In multiple cases, opposition fighters are seen affected by some kind of irritant. Phosphorus is sometimes mentioned, but may not be the only chemical involved.
  2. These cases are correlated with clashes between the regime and the opposition in the area, and nearly all victims are males of fighting age.
  3. The number of deaths reported in these incidents is very small and unverified.
  4. In most cases, the symptoms are not consistent with use of a nerve agent, including severe coughing, vomiting and pain that are not accompanied by loss of consciousness.
  5. Despite multiple claimed chemical attacks and the high availability of cameras, there is no documentation of an actual attack taking place or the munitions used. In a few cases, evidence of white phosphorus is seen.
  6. In multiple cases blood samples have been taken from victims and sent to countries friendly to the opposition. Given the political interests, it is safe to assume that when not reported otherwise, the results were negative.
  7. The Khan Al Assal attack is very different from the other cases: (a) victims are Syrian soldiers and regime-supporting civilians, (b) a significantly larger death toll, (c) the symptoms described are consistent with the use of a nerve agent, (d) environmental samples tested positive for sarin, and (e) the regime requested a UN investigation.
  8. In general, the effects of these attacks are negligible compared to the extent of the conflict. So if indeed a chemical attack is the cause it would have small military gain for the regime, but significant political gain for the opposition. This of course is not evidence in itself, but it does mean that much stronger evidence is required before accepting that the regime has used lethal chemicals.

Conclusion: The regime has used White Phosphorus and possibly less-than-lethal chemical agents against opposition forces. There are no reliable indications for nerve agent use by the regime. There is some evidence indicating the attack in Khan Al Assal was an opposition attack with a lethal chemical weapon.

Did I miss anything? Please share your evidence and analysis and help improve the conclusions.

In this report I found the compilation of evidence done by Wikipedia, acloserlookonsyria, Brown Moses, and George Washington University very helpful. All evidence was independently verified.


Gleb Bazov directed me to this research from the Harvard Sussex program on chemical and biological weapons. It analyzes the allegations of chemical attacks (including some that I missed), and reaches a similar conclusion that the Syrian Army has been using less-than-lethal chemical agents against opposition forces.


  1. Thank you Sasa for crediting our work at A Closer Look on Syria. There does not seem to be any other as comprehensive list of incidents and allegations around. Some people however think it is like Wikipedia and does not need to be credited.

    There is this video by "AMTV" that list the most important incidents:
    A Closer Look at Syria's 7 Deadly Chemical Attacks
    No mention of any source for their work. Interestingly, it may be the only source I know, apart from our site and a blog comment, that names chlorine as one of the likely agents used on August 21.

    1. You're welcome. Thank you for making it available.

      The video is nicely produced but uses so much faulty evidence that I prefer not to use it.

  2. Regarding the reported number of casualties, it appears that self-reported casualties may be five times actual casualties.


    "Because of the nature of nerve agents and the terror they create, psychogenic effects are very common following their use or perceived use. In the Iran-Iraq war, soldiers would frequently inject themselves with atropine and insist they had been exposed to nerve agents, when all evidence indicated that they had not been exposed (Newmark 2004a). In the Tokyo attacks, over 5000 persons reported to hospitals to be treated while, by the best estimate, only about 1000 people were actually exposed (WHO 2001). Because of the high prevalence of psychogenic effects and the need for immediate treatment upon actual exposure, it is important to be able to distinguish between psychogenic events and actual exposure."

    It may be that many cases self-reported gas victims at a location had never been exposed to Sarin.

    1. I'm not sure how strongly this applies to Zamalka:
      1. This is relevant to light injuries, not deaths.
      2. Hospitals in Ghouta were overwhelmed, so there was probably no attention given to anyone with mild symptoms.
      3. Tokyo is much more populated, meaning many more people that can be misdiagnosed.

  3. Correction to your paragraphs about Jobar 12-14 April and Saraqeb 29 April. This Le Monde report (http://www.lemonde.fr/proche-orient/article/2013/06/04/laurent-fabius-confirme-l-utilisation-de-gaz-sarin-en-syrie_3424140_3218.html) gives some information about the lab results. From Jobar, three urine samples tested positive for IMPA and from Saraqeb two blood samples tested positive for "regenerated sarin" (presumably the fluoride ion regeneration test for sarin-BChE adduct, harder to fake than the IMPA test).

    The paradox is that despite the positive tests for sarin, all those who have examined the reports of what happened in Saraqeb, including Brown Moses (http://brown-moses.blogspot.com/2013/05/was-attack-in-saraqeb-chemical-weapons.html) agree that it is highly unlikely that this was an attack using lethal chemical agents. The alleged means of delivery turns out to be plastic riot control grenades known to be in the hands of Jabat-al-Nusra. Yet according to the BBC one of those taken to hospital in Turkey died on the way (not clear if a sample from her was included in those sent to France).

    A possible explanation is that the riot control canisters were used to panic people into seeking medical attention for a chemical attack, and that sarin was subsequently administered surreptitiously to at least two of these people before they reached hospital in Turkey.

  4. "…let’s analyze the reports one by one…"

    No, no, no

    Let's say, smiling Franklin looks at you from 100-dollar bills - this banknote is a fake. You do not have to check all the remaining degrees of protection.
    It is similar, there is no means of delivery - no chemical attack Zamalka and nowhere else.
    Accordingly, the UN, Obama, Olland and all others should have an erotic journey to ass.

    1. What indications do you see that the evidence was fabricated?

    2. It is known to all - aerodynamic freak could not fly more than 2 km. This is totally enough.
      Therefore, do not need other fabricated evidence, a la, azimuth bent to the west by UN experts.

    3. But this is only relevant to the August 21st attack. No?

    4. Benjamin smiles
      / http://thumbs.dreamstime.com/z/funny-100-banknote-magnifier-13193990.jpg /
      The train has already left - was announced means of delivery.
      Only a fool believes a liar. Why do I have to check everything from Saddam's WMD?

  5. No satellite imagery,no communication intercept,no forensic evidence,no post mortem analysis,no proper body count,no ballistic testing, "the mysterious weapons" trajectory calculations are speculative at best.They have yet to define what specific type of ammo and delivery system was used during the alleged Ghouta attack.I wont even mention the "sites" selection & witnesses testimonies.
    In layman words,the so called UN report is a violation of every single scientific criminal investigation protocols.It reads like a UFO investigation report.

    So far we know that Bashar has CW capability,he probably has the determination to use his CW arsenal,but I am questioning the timing of his decision to use CW on Ghouta,which is in regard to Obama "red line" declaration,akin to committing suicide.Having said that,I have no trust in Russian explosive statements,they have yet to provide any evidence to back up their claims.What we have here is a game of counter propaganda Vs an official propaganda.

  6. For completeness sake, IMPA in blood of victims is marker for DIMP or Sarin. Dimp could have been administrated on its own without Sarin. Dimp is a lot less toxic than Sarin and is available on the market, sold by specialized labs.

    1. Interesting. Can you provide a reference?

    2. Wikipedia now lists IMPA as number 8 on its all-time high list of substances by non-toxicity – Right after water, table sugar, and vitamin C, on par with alcohol.

      The lethal dose (LD50) is 7000 mg / kg. For DIMP it is around 1000 mg / kg, meaning that an adult male could eat about 100 g before dying.

    3. Wikipedia is incomplete. IMPA is metabolite of Sarin and DIMP. They mention the lethal dose of IMPA, not Dimp...

  7. http://www.atsdr.cdc.gov/toxprofiles/tp119.pdf p3-4 The document states that through drinking DIMP contaminated water, the metabolite IMPA is generated in the bloodstream. I found other documents confirming that IMPA is not unique to Sarin, but is also a metabolite of Dimp (=byproduct of Sarin, NOT degraded Sarin). In other experiments described in other documents, animals are fed Dimp. If the chemicals could be obtained for the experiments, they can technically be obtained for other purposes. I guess a sophisticated organization backed by foreign intelligence services would have no problem getting DIMP in pure form. They don´t need to make it themselves.

    1. Added to the post.
      Thank you for contributing!

  8. Damn good compendium, SASA, apparent overall grasp and fair tone (didn't nit-pick through it though), nothing missing I noticed, and it runs a bit past our once-running tally at ACLOS. Sometimes I wonder if you must be more than one person, but I guess you do have good stuff (like ours) to start with, just like we have others' to start with (including yours, maybe). To add, only what'sso new you probably missed it, our Saraqeb, April 29 analysis taking off: http://acloserlookonsyria.shoutwiki.com/wiki/Talk:Alleged_Chemical_Attack,_April_29,_2013

  9. A very new report alleging a chemical attack in Jobar, 28 Nov 2013.


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