The United Nations Independent International Commission of Inquiry on Syria issued a report this September that reinforced the official narrative that the Syrian air force dropped a bomb containing nerve gas sarin on the insurgent-controlled town of Khan Sheikhoun, Syria on April 4. That conclusion comes several weeks after the Organization for Prohibition of Chemical Weapons (OPCW) issued a report that supported sarin exposure as the cause of death and injuries.
The reports by the two official international bodies appear to be aimed at closing the book on what happened at Khan Sheikhoun, where at least 83 deaths and 293 injuries occurred. But a months-long investigation by AlterNet into the questions around the attack raise serious questions about whether a sarin bomb was the source of the deaths. Relying on analysis from forensic and weapons experts, as well as a senior intelligence official with decades of experience in assessing bomb damage, the investigation suggests that a conventional weapon dropped by a Syrian plane struck barrels of a pesticide that created deadly phosphine gas that caused symptoms paralleling those of sarin and capable of causing mass casualties.
The evidence gathered in this investigation undercuts the credibility of the Organization for the Prevention of Chemical Weapons (OPCW) laboratory test results that showed exposure to sarin, demonstrating how the organization violated its own protocols and opened the door for tampering. Further, the investigation raises questions about whether Russian and Syrian intelligence knew — or should have known — that the conventional strike on the target in Khan Sheikhoun carried a serious risk of mass casualties.
At the center of the U.N. Commission’s case is a crater in the middle of a road in Khan Sheikhoun in which two metal objects were found. The shoddy narrative of a sarin attack carried out by the Syrian government has flowed from this hole in the ground.
The Sarin Bomb Crater That Wasn’t
The UN commission report refers to the crater as a “hole,” commenting that it was “too small to be a crater,” but pronounces it consistent with a chemical weapon. Without any reference to a source of evidence, it refers to the two pieces of metal as “two parts of the bomb.” Although it admits to being “unable to determine the exact type of chemical bomb used,” it declared the two pieces of metal to be “consistent with sarin bomb produced by the former Soviet Union in the 250kg-class of bombs.”
But for longtime analysts of weapons impacts, the scene provoked serious doubts. In interviews, two highly qualified former U.S. government specialists noted that a chemical weapon could not have made a crater as large and deep as the kind that appeared in a raft of reports about the attack on Khan Sheikhoun, especially in asphalt.
“I have never seen a crater like that from a 122 millimeter CW [chemical weapon) warhead,“ said a former senior intelligence official, with decades of experience in analyzing bomb damage, who did not wish to be identified because of his continuing work with U.S. national security officials.
That observation reflects a fundamental difference between chemical and conventional high explosives munitions. Chemical weapons have only very small amounts of explosives in the “burster mechanism”—enough to open up the bomb to disperse the chemical, but not enough to cause a crater in the pavement. If a chemical munition had contained enough high explosives to create a large hole in the pavement, it would have burned up the chemical to be dispensed and could not have caused the mass casualties seen in Khan Sheikhoun.
The former senior intelligence officer declared the metal detritus inside the crater was staged. “I am certain that it was placed there after the fact,” he said. “The entire set-up looked like a pothole with a pipe over it, not a military explosion or impact.”
Pierre Sprey, an aeronautical engineer who spent many years at the Department of Defense as a weapons analyst, also doubted that the scene at the crater was genuine. “I have viewed the images of many, many weapons impacts of all kinds, and the photos didn’t look like any impact crater I’ve ever seen,” he said. Sprey said the site “looked more like a pothole than anything else—much more that than a weapons impact.”
Further undermining the credibility of the sarin attack narrative is the absence of any weapon. The main pieces of any chemical weapon should have fallen, still intact, just a few meters away from the crater, according to John Gilbert, senior science fellow at the Center for Arms Control and Proliferation and formerly head of the Onsite Inspection Agency in the Defense Department. Gilbert conducted the inspections of the former Soviet chemical arsenal in conjunction with the U.S.-Soviet 1990 chemical weapons agreement.
Sprey agreed that intact pieces of the weapon should have been found. “Without a shadow of a doubt you would have found the tail fins and nose cone,” said Sprey.
Not a single recognizable fragment of a weapon that could have delivered sarin gas was ever displayed in videos or photographs taken by the White Helmets or Syrian rebel media activists in Khan Sheikhoun. Solvang, the main author of the Human Rights Watch report on Khan Sheikhoun published May 1, acknowledged in an interview that he had asked all the personnel of the White Helmets civil defense organization and other witnesses interviewed by his organization whether they had seen any other parts of a weapon. All responded in the negative. (The White Helmets is a Western and Gulf-funded arm of the Syrian insurgency that is primarily responsible for influencing foreign news media and opinion for al local al Nusra Front officials).
Chunks of asphalt would also have been strewn around the crater by an airstrike. “Debris would be blown several meters away from the crater,” Gilbert noted in an interview. But independent Berlin-based forensic researcher Michael Kobs discovered footage suggesting no debris was on the road near the crater after that morning.
Kobs noticed a brief scene in a video published by Orient News Service on April 4, less than two hours after the alleged explosion at the site, showing (at 1.12) the road near the crater completely clear of pieces of asphalt and other debris. Using standard forensic techniques for estimating the time an image was taken based on the length of a shadow in relation to a fixed object, Kobs calculated that the video was shot between 8:30 and 8:50am, on April 4. The airstrike took place around 6:40-6:45 am, according to most witnesses.
Kobs found another video published April 6 that shows all the chunks of asphalt had been moved by hand to an area roughly five meters wide and two meters deep by the side of the road. The White Helmets or other health authorities authorities had placed the same red sign with skull and crossbones over the asphalt pieces that had been put inside the crater itself.
If a chemical weapon had exploded at that spot, the chunks of asphalt dislodged from the crater would have been covered with sarin liquid, which would have taken far more than a couple of hours to dry in the cool morning air. So any contact or inhalation near them would have been highly lethal.
Furthermore those two hours were the period during which the White Helmets and the Idib Health Directorate were engaged in taking dead and wounded to the White Helmet facility east of the Khan Sheikhoun. Given the extreme dangers associated with the handling of objects contaminated with sarin, the idea that the local government ordered civil defense teams to cart chunks of asphalt drenched in sarin away from the road during that first hour and a half seems absurd.
The video evidence indicates that the road near the crater was already clear before April 4 and the crater was therefore not the result of an air attack that morning. It now appears that the hole was either the remains of a previous military event or simply a pothole that had been filled in with dirt but not repaved. A video shot several hours after the chemical incident shows (at 3:04-3:08) what appears to be two large potholes within a few yards of the crater, both of which had been filled in with dirt but left unpaved.
Further evidence that the toxic gas that killed and injured residents could not have come from that crater can be found in the June 29 report of the Organization for the Prohibition of Chemical Weapons. Though the report concluded that sarin gas was used, and that it “likely” emanated from the crater, Figure 7 of the report contradicts these findings.
Figure 7 (seen above) provides an aerial view of Khan Sheikhoun, with the area where victims were stricken shaded in yellow. The image highlights the crater in red and labels it as “point 1,” and shows that the point lies only a few meters east of a residential neighborhood. Yet no part of that neighborhood is shaded yellow, meaning that no one in the immediate vicinity of the supposed blast site was exposed to a toxic gas. The OPCW did not explain how residents living just meters away from the scene of a chemical attack could have suffered no ill effects.
The U.N. Commission’s claim that the two pieces of metal found in the hole in the road were parts of the bomb dropped on the site relied on a report on Khan Sheikhoun issued by Human Rights Watch. HRW asserted that the large piece of metal and the small cap that had been shown in various positions in the crater could have been parts of a Soviet-era chemical weapon designated as KhAB-250. HRW argued that the KhAB-250 “has two green bands” supposedly used to indicate a chemical weapon, and that the piece of metal found in the crater had what appeared to be a green stripe on it. It also said the filler cap ”appears similar” to the cap covering the filling hole of that bomb.
That HRW claim was in turn apparently based on a tweet that itself relied on a Russian researcher who acknowledged that his assertion was just a hypothesis.
It is now clear that HRW’s theory was completely unfounded. An official historical study of Russian bomber armament up to 1945 published by Russian Federation General Staff in 2001 indicates the KhAB-250 was put into service in 1945. Soviet production of sarin did not even begin until 1958-’59. The Soviets discontinued the KhAB-250 50 years ago, according to Russian Ministry of Defense spokesman Gen. Igor Konashenkov. Furthermore, there is no evidence that the KhAB-250 was ever exported by the Soviet Union to Warsaw bloc allies or Middle Eastern regimes. The only photographs of the KhAB-250 available on the internet are from the military museum in Moscow.
Even if a KhAB-250 had somehow appeared in Syria, the bomb could not have made the crater shown to the world as the site of a sarin attack, according to Gilbert. If it had, Gilbert explained, “the crater would have been several times larger.”
Independent forensic researcher Kobs has disposed of the idea that the filler cap had anything to do with a KhAB-250 bomb, showing that the side of the cap, or nozzle, HRW suggested was similar to the KhAB nozzle actually goes inside a bomb rather than on its outside surface. After an exhaustive search of images of Russian bombs, Kobs found only one bomb whose filler cap came anywhere close to resembling the side of the cap that would be visible: the OFZAB-500 fragmentation incendiary bomb. The two bolt holes in the OFZAB-500 filler cap are not in the same place as the one photographed at the site. The OFZAB-500 is one of the bombs Syria reproduced with Iranian aid during the present war, so it could have been slightly redesigned. But it is not capable of delivering a chemical weapon.
The evidence now available makes it clear that the scene suggesting a sarin attack at the crater was a crudely staged deception. Al Qaeda and Ahrar al-Sham, the Salafi-jihadi militias that were in firm control of Khan Sheikhoun, had a powerful incentive to present such a scene or pothole to global news media as the attack site. These armed groups would have been deeply unsettled by signs on the eve of the event that the Trump administration was withdrawing support for anti-government forces. But they were also keenly aware that the U.S. news media had long embraced a hard line against the Assad regime, and that Washington was likely to respond strongly if presented with what appeared to be evidence of a mass casualty sarin attack.
It was not the first time that those working under al Qaeda authority had arranged a falsified bomb crater scene to shape international opinion. After an attack on a Syrian Red Crescent aid convoy west of Aleppo last September, the White Helmets photographed the crumpled tailfin of a Russian OFAB-250 bomb in a crater in a warehouse. But a bomb of that weight would have made a much larger and deeper crater. The only plausible explanation was that the OFAB-250 tailfin had been planted there after the fact.
How a Pesticide Caused Mass Casualties in Khan Sheikhoun
The U.N. Commission report says it investigated claims by Russian and Syrian officials that a Syrian airstrike hit a “weapons depot” and having found them to lack credibility, determined that there are “reasonable grounds” to believe that the casualties were the result of a Syrian air force sarin attack. But the evidence now available leaves little doubt that both the initial Russian and Syrian government explanation and the local government-White Helmet explanations have deliberately obscured the real cause of the mass casualties
Eyewitness accounts of the airstrike, the revelations in Seymour Hersh’s article in Die Welt and other information about the building hit by a Syrian bomb, the geographic pattern of the casualties, the known characteristics of aluminum phosphide and the symptoms of the victims all indicate a very different explanation: A Syrian high explosive bomb hit supplies of aluminum phosphide stored in a building in the northeast area of Khan Sheikhoun, releasing a cloud of deadly phosphine gas, which caused the deaths and injuries.
Syrian and Russian government statements about the event have confused the issue by insisting that the Syrian airstrike took place at 11:30am, rather than before 7:00am. Russian Defense Ministry Spokesman Maj. Gen. Igor Konashenkov said the target was “near Khan Sheikhoun” rather than in the city itself. That was an obvious effort to conflate the early morning airstrike with a second airstrike later that morning on a complex run by the White Helmets civil defense organization east of Khan Sheikhoun, that included an underground medical facility as well as offices and storage areas.
Konashenkov described the target of the strike as a “terrorist warehouse” where bombs had been made that “contained toxic substances.” The spokesman said the alleged warehouse had stocked the same chemical weapons that had been used by rebels in Aleppo, and that the symptoms shown by Khan Sheikhoun victims in videos were the same as those exhibited by victims of chemical weapons in Aleppo.
But contrary to the official Syrian and Russian account, the main target of the airstrike was clearly not the complex east of Khan Sheikhoun, but a building in Khan Sheikhoun itself. Accounts from a number of eyewitnesses indicate that an airstrike hit a two-story building about 240 meters southwest of the crater the local authorities and activists claim had been left by the strike, as well as a second building another 100 meters southwest. Photographs in a report by activists belonging to NGOs who support the armed opposition show (pp. 34-35) what had been a two-story cinderblock building that was completely destroyed by the airstrike.
The U.N. Commission does not deny that a strike hit targets other than the crater but simply ignores the evidence that the northernmost of those two buildings was the source of the deaths and injuries. Eyewitness accounts confirmed, however, that the bomb that destroyed the building was also the source of a lethal toxic chemical cloud. A 14-year-old eyewitness told the New York Times she saw a bomb dropped on a building at that time in the morning create what she described as a yellow mushroom cloud that stung her eyes. Another witness said she heard a loud explosion and saw a yellow-orange cloud, and that her daughter inhaled the gas from that cloud and died very soon after from its effects.
It turns out that one of the alleged eyewitness cited by Human Rights Watch as having seen a bomb being dropped at the crater site was actually watching the bomb that destroyed that building. Ahmed al-Helou, a farmer who was on a hill at an unspecified distance east of the city, told Human Rights Watch he saw the bomb fall “in front of” the central bakery—meaning west of the bakery, which faces the main road—and that it created “yellowish smoke.” But as the Google Earth aerial view of the area of Khan Sheikhoun below shows, the central bakery is not east of the now infamous crater; it is about 50 meters south of it. The cinder block building demolished by the bomb, however, is about 200 meters west of the bakery, so the bakery would have been between al-Helou and the demolished building. He saw the same explosion and yellow smoke as the other two eyewitnesses.
Western mainstream media reported that the symptoms experienced by victims of toxic gas exposure were consistent with exposure to sarin, and treated them as clear evidence of a sarin attack. But what those reports failed to mention was that those same symptoms are also consistent with exposure to phosphine gas, and that two reported symptoms of victims could only have resulted from phosphine gas exposure.
The symptoms common to both sarin and phosphine poisoning include chest tightness, difficulty breathing, dizziness, excessive salivation, tearing, lethargy, drowsiness, fatigue, loss of feeling, impaired gait, convulsions, blurred vision, vomiting and diarrhea. Both sarin and phosphine can also cause cyanosis, or bluish discoloration of the skin.
But two more symptoms reported to have been experienced by victims in Khan Sheikhoun are linked to phosphine exposure and could not have been produced by sarin. The nurse who treated victims at al-Rahma hospital that morning recalled that injured patients were vomiting from the nose and mouth, and that their vomit had created dark yellow stains around the mouth that sometimes turned to brown. When phosphine gas burns it forms phosphorus pentoxide, which reacts with moisture in body tissues to create highly corrosive phosphoric acid. This effect is what accounts for vomiting that leaves yellow or even brown stains around the mouth.
Bleeding from the mouth, another unique symptom of phosphine exposure, was described by an eyewitness in an AFP video. A media activist at the same hospital where 18 severe cases were being treated confirmed that symptom, recalling that as they were administered oxygen, the victims bled from the nose and mouth. That symptom, too, is associatedwith exposure to phosphine gas but not with sarin exposure. Examination of autopsy reports from phosphine poisoning deaths has shown that they have frequently found bloody frothing from the nose after the lungs began to fill with blood.
The evidence from eyewitnesses, the data from OPCW itself on the location of the victims, the background of Syrian concern about aluminum phosphide, the nature of the phosphine gas it released and the symptoms displayed by the victims is all at odds with with official narrative of a sarin attack at the site of the crater. That evidence strongly suggests that the al Qaeda authorities in Idlib successfully foisted a tale of a Syrian government sarin attack on mainstream Western media and governments, the OPCW and now the U.N. Commission of Inquiry.
The initial Russian-Syrian account of the event also distracted attention from the real Syrian airstrike in Khan Sheikhoun and the question of what they anticipated would be the consequences of bombing supplies of aluminum phosphide. But any effort to hold them accountable for that actual strike can only came when Western governments acknowledge that the alleged sarin attack on Khan Sheikhoun was a fiction.
How the OPCW Produced False Positives for Sarin Exposure
OPCW’s fact-finding mission’s June 29 report was universally regarded as presenting laboratory test results confirming that the deaths and injuries in Khan Sheikhoun were from a sarin attack. The report does indeed show largely positive test results for exposure to “sarin or a sarin-like substance,” as OPCW phrased it.
But the two types of tests OPCW relied on to produce those results can both produce false positives for sarin exposure. As this report reveals, one of the tests carried out by laboratories for the OPCW can be manipulated before biomedical samples are taken to produce the desired test result. As for the second test, its conclusion was fundamentally flawed, as it ignored the fact that exposure to phosphine gas would have brought about precisely same test results that were attributed to “sarin or a sarin-like” chemical weapon.
Neither of the two OPCW laboratory tests can detect directly the toxic gas to which the victims were exposed. The OPCW network laboratories relied on gas or liquid chromatography to look for a specific metabolite or breakdown compound, as they could not have identified sarin itself. Sarin breaks down rapidly in the human body into a metabolite called isopropyl methylphosphonate. IMPA is the first compound for which the laboratories test, and finding it in a blood, urine or tissue specimen has long been considered evidence of exposure to sarin.
But that test can be fooled. As even a cursory internet search will demonstrate, isopropyl methylphosphonate is sold commercially by major chemical companies. And IMPA is not only safe to handle but was found by the EPA to be harmless when consumed orally at doses of 3,000 parts per million. In order to produce positive laboratory test results showing exposure to sarin, this substance could be administered in a hydration drip or glass of water before a biomedical sample is taken from the test subject.
Two scientists with close ties to the OPCW, both intimately familiar with the organization’s testing for exposure to sarin and other nerve gases, acknowledged in e-mails that administering commercially available IMPA to a person before biomedical samples were taken would indeed show up in the OPCW lab test as a positive for IMPA. Both scientists insisted on anonymity in responding to queries.
“If you injected IMPA into people whom you then present as victims, you would indeed find it in the urine,” one scientist who has worked closely with OPCW said in an email. The other scientist said, “As far as I am aware the metabolism of IMPA has not been studied, but it is likely that following ingestion or administration some would appear in the urine unchanged.” Neither of the scientists contested the fact that the test for IMPA in urine samples could have produced false positives.
The laboratory results for biomedical samples taken without OPCW personnel present provide evidence that biomedical samples were taken after administering IMPA to the subjects. According to specialists who had tested biomedical samples for sarin exposure, the metabolite of sarin can rarely be detected after a week. Yet biomedical samples of alleged attack victims were transmitted to the OPCW team between April 12 and 14—from eight to 10 days after their exposure to chemicals in Khan Sheikhoun. And every one of the seven urine and hair samples submitted by the Idlib Health Directorate—which operates under the control of al-Qaeda and its allies in the province—was positive for IMPA.
Biomedical samples submitted during that same period more than a week after the toxic chemical event by the Syrian American Medical Society—a non-profit, pro-opposition organization that works closely with the al Qaeda controlled health service in Idlib province—provided further evidence of tampering. Three of the seven blood samples tested negative for “sarin or sarin-like substance,” indicating that those three had not been exposed to a nerve agent. Yet two of the three urine samples and all three of the hair samples from those who had clearly not been exposed tested positive for IMPA, the substance that can be administered to produce false positives for the breakdown product of sarin.
The OPCW report itself recognized those results as irregularities but did not acknowledge that they indicated an obvious manipulation of the sample-taking by those institutions.
While acknowledging, in effect, the possibility of a false positive on the test for IMPA as the biomarker for sarin, both scientists asserted that other OPCW tests were used to confirm the positive results of the test for IMPA. The OPCW test to which they were referring is called a “protein adduct” test and is much more elaborate than the test that seeks to identify IMPA. They try to regenerate part of the compound representing the organophosphorus nerve agent that binds to acetylcholinerase (AChE) or butyrylcholinesterase (BChE) enzymes in human cells in order to confirm the nature of the compound to which a victim has been exposed.
But these tests do not identify the specific nerve agent involved. They can only confirm exposure to a type of chemical that can bind with those enzymes and cause them to cease functioning. The OPCW confirmed that fact in a 2014 article on its protein adduct test, explaining that the adduct reproduced by the test may appear identical to the one produced by exposure to sarin, but may actually be the result of exposure to VX nerve gas. That explains why the OPCW adopted the phrase “sarin or a sarin-like substance” in reporting the results of the protein adduct tests on biomedical sample from Khan Sheikhoun.
The OPCW, which is only concerned with chemical weapons, never considered the possibility that the organophosphate toxic agent that was reflected in those tests results was phosphine gas. Experts on phosphine have long known, however, that among other toxic effects on the human body, phosphine gas disrupts the supply of acetylcholinesterase—just as sarin and other officially recognized nerve gases do. William Potter of the Department of Chemistry and Biochemistry at the University of Tulsa was the lead author of an early study on the effect of exposure to phosphine gas on acetylcholinesterase levels in agricultultural workers, including those who applied phosphine. Potter told AlterNet that whenever phosphine gas enters the human body, “it forms reactive phosphorus intermediaries that would inhibit acetylcholinerase in a manner very similar to known chemical weapon nerve gases.”
Phosphine’s intermediaries would have such an effect by binding to enzymes that regulate nervous system transmission, Potter said. And that effect could have been reflected in OPCW laboratory tests of victims of phosphine exposure, according to Potter. “Laboratory tests on blood samples from someone exposed to phosphine,” he said, “would indicate several different reactive phosphate derivatives that inhibit esterase enzymes.”
But Potter added that the laboratory tests probably would not have recognized it as the signature of a phosphine derivative, because they were only expecting to find sarin or another weaponized nerve agent.
How OPCW Violated Its Own Protocols
The OPCW report also presented the results of laboratory tests of the environmental samples in and near the crater that was alleged to have been the site of the Syrian military’s bombing, as well as from a goat and several birds. But the OPCW had no verifiable chain of custody of the samples, meaning that the organization did not see them collected, so al Qaeda-directed personnel could have manipulated the samples either before or after collection. The samples in and around the crater were collected by the “chemical sample unit” of the White Helmets civil defense organization, which was also responsible for media and foreign opinion operations in relation to the toxic exposure event. In Idlib, the White Helmets function entirely under the authority of the province’s al-Qaeda leadership.
Dr. Theodore Postol of MIT, who examined the video of the White Helmets collecting the samples, noted in an interview that the video shows the White Helmets violating the most fundamental rules of sample collection and systematically cross-contaminating the samples. The teams of civilian volunteers used the same tools repeatedly for different samples, put them in plastic bags only loosely tied at the top and then mingled all the samples together in one relatively small box.
Watch | White helmets collect “sarin” samples
The OPCW report cited the fact that the government of the Syrian government had provided a series of environmental samples as evidence, and even suggested that the government did not question the OPCW’s overall conclusions. But the details of that data do not support the latter assertion. Although the samples from soil and metal objects in the crater said to have been taken on the Syrian government’s behalf and tested in its laboratories all registered as positive for sarin, those samples could have easily have been contaminated from the start with a few small vials of sarin. On the other hand, all but one of the 14 soil samples analyzed by the government laboratory outside the crater registered nothing of significance.
In citing the positive test results on environmental samples and reporting on biomedical samples taken by one of the parties in support of its conclusion that sarin had caused the deaths and injuries in Khan Sheikhoun, the OPCW violated one of its most fundamental rules. It is forbidden from using any biomedical or environmental samples as evidence unless they have a verifiable chain of custody, as a spokesman for the organization clarified when allegations of chemical attacks first arose in Syria four years ago.
The OPCW itself took no samples of any kind in Khan Sheikhoun because its fact-finding mission never set foot in the city. Instead, it performed all of its work in Turkey or elsewhere in locations in Syria controlled by al Qaeda or another rebel group. That, too, was an explicit violation of the organization’s own rules. The same OPCW spokesman who insisted that OPCW could only use evidence with a clear chain of custody also told reporters in 2013 that the OPCW was not supposed to rule on whether an attack with banned chemicals had taken place without direct access to the relevant site. At no point did any OPCW inspector come within 100 miles of the alleged attack site in Khan Sheikhoun.
Despite this flagrant breach of its own protocols, the OPCW has faced no real scrutiny from Western mainstream media. The disinterest of the international press corps in raising any questions about the OPCW’s methodology or probing the actual evidence surrounding the event has reinforced the initial story spun out by al Qaeda-tied media activists. The same pattern of passive acceptance of the official narrative is now continuing with the coverage of the U.N. Commission report, which is received as gospel despite its flaws. But as this investigation has demonstrated, the official narrative on Khan Sheikhoun doesn’t hold up under scrutiny.
Top photo | Close up photograph of the crater that has been shown in numerous mainstream media publications that the White House alleges is proof that the source of the nerve agent attack was the Syrian government.
Gareth Porter is an investigative historian and journalist specializing in U.S. national security policy. His latest book is Manufactured Crisis: The Untold Story of the Iran Nuclear Scare (Just World Books, 2014).