Bashar al-Assad
Bashar al-Assad; drawing by Siegfried Woldhek

In late June, the Organisation for the Prohibition of Chemical Weapons (OPCW) released a report on the April 4, 2017, nerve gas attack on the central Syrian town of Khan Sheikhoun, a civilian area under rebel control in which there was no fighting at the time. An estimated one hundred people died; another two hundred suffered from acute exposure to the gas. The OPCW’s report persuasively showed that the agent used in the attack was sarin. The investigators, who did not have access to the site, could not determine the method by which it was dispersed, but they concluded that “the exposure was likely initiated from a release in the vicinity of a crater in the road, located close to the silos in the northern part of town,” where eyewitnesses said a plane had dropped a bomb.

The OPCW’s fact-finding mission was established in a mandate by the UN Security Council that specifically limited its scope to “not include the task of attributing responsibility for the alleged use [of chemical weapons].” But nevertheless the report implicitly blamed the regime of Syrian President Bashar al-Assad, which is the only participant in the Syrian conflict capable of carrying out a nerve gas attack by air.

Assad’s most powerful international supporter has been Russia, which sent its forces into Syria in September 2015 to bolster his struggling regime. Within hours of the attack, the Russian Defense Ministry acknowledged that there had been a Syrian air force strike on Khan Sheikhoun, but claimed that it had taken place later in the day, in a different part of town, and targeted a facility in which rebels manufactured and stored shells containing toxic gas for use in Iraq. According to the Russian account, the explosion released these gases into the air, with lethal effect.

Russia is a party to the Chemical Weapons Convention and has largely eliminated its own chemical stockpiles. It has no obvious interest in the proliferation of chemical weapons, and supported the OPCW’s earlier effort to eliminate the Assad regime’s chemical stockpile following a sarin attack on the Damascus suburb of Ghouta in August 2013 that killed hundreds. The Russian government therefore, to avoid embarrassment, desperately needed an alternative explanation for the sarin attack on Khan Sheikhoun, particularly since it must have known that the Syrian government was responsible: Russian military advisers were stationed on the airbase from which the plane carrying the chemical weapons had taken off.

The story the Russians came up with, however, makes no sense. Even if a facility like the one they described existed, it would not have stored sarin itself but rather its chemical components, which are combined only when loaded into a munition. An air strike on such a facility would not have released sarin gas but destroyed its component chemicals. Still, the story soon found Western backers. These included nominal Trump supporters with an affinity for conspiracy theories (notably concerning the Ghouta attack), such as Veteran Intelligence Professionals for Sanity, an organization of former US intelligence analysts, and Alex Jones’s Infowars website. Such backers either blamed al-Qaeda and other rebels or claimed that the attack was an operation funded by George Soros in the expectation that the Assad regime would be blamed. These stories were widely retweeted when they were published in April.

Others who bought into Moscow’s story may have done so out of sympathy for the Assad regime or out of contrariness. These included Theodore Postol, an MIT professor with expertise in missile technology but not chemical weapons, as well as at least three award-winning US freelance journalists: Seymour Hersh, Gareth Porter, and Robert Parry. Hersh, for example, advanced an explanation that exonerated the regime even if it did not fully follow the Russian version of events. Moscow was able to mobilize such views in its effort to protect Assad from international censure, which included vetoing a resolution in the Security Council condemning the attack.

This was not the first time a country escaped condemnation after a powerful ally spread disinformation about a chemical attack. On March 16, 1988, toward the end of the Iran–Iraq War, the Iraqi air force unleashed a nerve gas attack on the Iraqi-Kurdish town of Halabja, killing an estimated five thousand civilians and injuring thousands more. (The precise number is unknown.) The town had been captured by Iranian forces, aided by Kurdish peshmerga insurgents, two days earlier. The Halabja atrocity was the worst of many chemical attacks over the previous five years by the Iraqi regime against Iranian troops, peshmerga fighters, and Kurdish civilians in both Iran and Iraq.

The attack was a potential source of embarrassment for the United States. Though the American government had stayed neutral in the early stages of the Iran–Iraq War, in the aftermath of the Islamic revolution and the US hostage crisis it could not bear the possibility of Iran winning the war and gaining more influence in the Gulf. The Reagan administration provided military assistance to Saddam’s regime, including access to satellite images that allowed Iraqi forces to target Iranian positions more accurately, especially with chemical strikes. The sharing of military intelligence was channeled through the Defense Intelligence Agency (DIA).


Within days of the Halabja attack, the US Department of State, guided by the DIA, promoted a story that it had been carried out at least partially by Iran. The Iraqi government, which had previously remained silent, spoke up in support of the American version of events. To make its story more convincing, the DIA referred to supposed international experts who had examined some of the evidence, mainly impressions on the ground in Halabja and photos of the deceased. These freelance investigators included two national section heads of Doctors Without Borders (both medical doctors) and a Belgian pharmacologist. None had known expertise in chemical warfare agents, and they made a misdiagnosis.

Even though a subsequent report by a UN chemical weapons expert team did not explicitly attribute responsibility to any party, the UN Security Council evidently knew that the Iraqis had carried out the chemical attack on Halabja. One of the investigators stated this to me in an interview after he retired, and even at the time they reportedly discussed their findings in the corridors of the UN. Even so, the UN Security Council passed a resolution in May 1988 that condemned the use of chemical weapons and urged “both parties” to refrain from using them in the future. My own research shows that the claim of Iranian complicity in the attack was concocted by the DIA to allow Iraq to prevail in the battles that would end the war. I have yet to find strong evidence—in declassified US intelligence documents or elsewhere—that Iran used chemical weapons at any time during the war. These documents and sources leave no doubt, on the other hand, that Iraq used them repeatedly.

In both Halabja and Khan Sheikhoun, it was not the perpetrator who spun the cover story but its international supporter; the guilty regime then merely repeated the story and added a degree of vagueness that further obscured what had actually taken place. The UN report on Halabja and the OPCW report on Khan Sheikhoun, both based on investigations by chemical weapons experts, are impressive in their scientific rigor and evident neutrality, yet exasperating in their inability to identify the perpetrator, due to the restrictive mandates imposed on their authors. If one knows the capabilities of the belligerents involved, however, it can be gleaned from these reports who their authors believe was responsible. Yet the reports’ failure to explicitly identify the perpetrators left them vulnerable to political manipulation.

Although it is categorized as a weapon of mass destruction, poison gas has rightly been banned primarily as an abhorrent instrument of war. It tends to be more effective in provoking terror and mass panic than in killing large numbers of people, with notable exceptions. Nerve gas is particularly insidious. It is a colorless, odorless, and tasteless liquid that evaporates upon release and asphyxiates its victims. Mustard gas, as well as the cruder chemicals chlorine and phosgene, was used extensively in the trenches of World War I, and it was the horrific sight of the victims and the immense suffering of mustard gas survivors, even many years later, that stirred the victors to institute a ban against the use of chemical weapons in the 1925 Geneva Protocol. Partly as a result, chemical weapons were not used on the battlefield in World War II.

Militaries consider chemical weapons a potential “force multiplier.” By gassing rear positions and supply lines, a military can reduce the number of soldiers it needs in battle. During the Iran–Iraq War, Iraq became the first country since World War I to significantly violate what had become a powerful agreement against their use (Egypt allegedly used poison gas on some occasions during its war in Yemen in the 1960s), in part because Iran had a larger population to draw on for fresh recruits; Iraq was also the first country to use nerve agents and to use chemical weapons against civilian populations.

In response to this profoundly alarming development, which raised the possibility of proliferation in the volatile Middle East and beyond, the international community convened a conference in 1989 to ban chemical weapons. This initiative—strongly supported by the United States—led to the 1993 Chemical Weapons Convention and the creation of an organization overseeing its implementation, the OPCW. The convention banned not only the use but also the manufacture, stockpiling, and trade of chemical weapons. Syria became a signatory to the convention under international pressure after it launched the chemical assault on Ghouta in August 2013, yet it continued to use chemical weapons against civilians, mainly the less lethal agent chlorine.


For the Syrian regime, chemical weapons have helped address the problem of its dwindling army. To a regime that has found itself strained and threatened by insurgencies, the use of such a horrific weapon means nothing, especially if it has already used many other violent and indiscriminate means, such as barrel bombs. The OPCW failed in its effort to completely destroy Syria’s chemical weapons and raw materials in 2013–2014 because the regime had hidden some of them. The Khan Sheikhoun attack was the most dramatic evidence of this.

Russia must have decided that its support for the Syrian regime outweighed its determination to uphold a comprehensive ban against chemical weapons (the Reagan administration made a similar decision during the Iran–Iraq War). While this is deeply troubling, it is not unreasonable to think that Moscow may join international efforts to reinstate the ban once it is confident that the Syrian regime’s survival has been secured—just as the US did after 1988.

Those who defend Syria insist that the Assad regime could not have been responsible for the Khan Sheikhoun attack because it had no reason to carry it out; in early April, it had put the rebels on the defensive and appeared stronger than it had for some time. But every participant in the Syrian conflict has a motive to use any weapon available to secure its own survival. This includes the regime, which is severely weakened even as it continues to be unremittingly brutal and which, at the time of the Khan Sheikhoun attack, faced deep morale and recruitment problems as it was fighting on several fronts.

Moreover, there is a well-documented record of its having used poison gas, including sarin, since late 2012; and it is alleged to have continued using chlorine since April, when the outcry over Khan Sheikhoun induced it to stop using sarin. Assad, like Saddam Hussein in the 1980s, is continually testing what he can get away with. When confronted with evidence of heinous acts, he retreats momentarily but then resumes with a lower profile. After all, the world’s attention span is only a few days long, if that. Assad has tried to shift the blame for individual attacks to ISIS, which also has used chemical weapons, mainly chlorine and mustard gas, in both Syria and Iraq, but could not possibly have carried out the sarin attacks on Ghouta or Khan Sheikhoun.

As with previous UN and OPCW reports on alleged Syrian chemical weapons use, Russia dismissed the OPCW report on Khan Sheikhoun, charging that it was based on questionable data from dubious sources. Meanwhile, the UN Commission of Inquiry on Syria, which had published a report on a separate investigation in August, concluded that the Khan Sheikhoun attack had been carried out by the Syrian air force. On October 26, the UN-OPCW Joint Investigative Mechanism, established by the Security Council in 2015, released a report on the attack conclusively identifying the Syrian regime as the perpetrator. Even persuasive evidence of regime culpability is unlikely to persuade Russia, a member state of both the UN and OPCW, to change its position, in view of the stakes involved: it cannot afford to let its client down while the war’s outcome remains uncertain.

Independent fact-finding is imperative to postwar efforts to reestablish an international agreement against chemical weapons use. Nonpartisan organizations with the requisite technical expertise such as the OPCW, UN commissions, and NGOs continue the hard work of establishing these facts. They interview eyewitnesses (including victims and medical personnel), collect and analyze evidence (including biomedical specimens from human and animal corpses, environmental samples, and remnants of munitions and fuses), and examine satellite imagery, flight records, and other primary materials. This work cannot be done quickly. In an age when “fake news” can decisively shape the public understanding of war crimes such as chemical attacks, it is crucial that the international community support their investigations and that it oppose deliberately misleading accounts that shield the perpetrators of chemical attacks.

The instinct to question official accounts is healthy and admirable, and global powers have been shown to have lied or obscured truths about tragic events. Yet extending this skepticism to work done by independent international agencies with proven expertise is dangerous. It is this expertise, and the agencies’ reputations, that will inform efforts to deter future use of chemical weapons. The OPCW and UN investigations may convince Russia that, although it covered up the truth of the Khan Sheikhoun attack, it has an overriding interest, as the US did before, in enforcing the ban on chemical weapons if and when it feels the Syrian regime is secure.

—November 20, 2017