In 53 years of Assad family rule, The Syrian regime manufactured tons of chemical weaponsfrom mustard gas from World War I to lethal nerve agents like sarin. However, what worries the international community most are not the chemicals destroyed, but those that he disappeared without a trace.
According to international inspectors, more than 360 tons of mustard gas and 5 tons of sarin nerve agent precursors were never fully accounted for. Bashar al-Assad’s government claimed that some materials were lost in transportation accidents, an explanation considered implausible by experts.
Concern is intensifying following the recent takeover of Damascus and other major cities by rebel groups. In a context of power vacuum, the risk of these weapons falling into the hands of terrorists, such as the Islamic State, or uncontrolled armed groups has set off alarms not only in Syria, but throughout the world.
Sarin, one of the most lethal substances produced by humans, can cause hundreds of victims with just a small amount. According to Gregory Koblentz, director of the biodefense studies program at George Mason University, the threat of these chemical weapons persists as one of the darkest legacies of the Assad regime. “Although Assad is no longer here, the specter of chemical weapons is still present in Syria,” he told The Washington Post.
Syria began developing chemical weapons in the 1980s as a deterrent against Israel, its main enemy in the region. As the Syrian civil war escalated in 2011, the regime used these internationally banned materials against rebels and civilians.
The deadliest attack occurred on August 21, 2013, when sarin-laden missiles hit rebel suburbs east and south of Damascus, leaving more than 1,400 dead, mostly women and children, according to U.S. estimates. This event generated global condemnation and forced Assad to admit the existence of his chemical arsenal, pledging to destroy it under international supervision.
Following international pressure, Syria destroyed approximately 1,400 tons of chemical weapons between 2013 and 2014, according to data from the Organization for the Prohibition of Chemical Weapons (OPCW). However, Western and Middle Eastern intelligence agencies suspected from the beginning that the regime had hidden part of its arsenal. This hypothesis was confirmed in 2017, when Syrian forces used sarin in an attack on a rebel-held city.
Despite international commitments, numerous inconsistencies in the regime’s reporting have left a dangerous gap in accountability. According to records analyzed by the OPCW, Syria produced 385 tons of mustard gasbut could only justify the destruction of approximately 20 tons. Syrian officials claimed that the rest had been cremated, but presented no credible documentary evidence to support this version.
The sarin case raises even more worrying questions. A chemical precursor known as methylphosphonyl difluoride (DF), necessary to manufacture sarin, has a deficit of 20 tons in official records. Syrian officials stated that a quarter of this chemical was lost in transport accidents, while the rest would have been used in military tests. Both explanations were described as “unlikely” by international inspectors.
These materials, although potentially degraded by time, could still be used in smaller scale attacks or as weapons of terror. “Although deteriorated, they can still be effective as weapons of terror“, he stated to The Washington Post Jerry Smith, former chief of operations for the joint OPCW-UN missions in Syria.
The recent collapse of the regime has created a power vacuum in which armed groups compete for control of territory. The main rebel faction, Hayat Tahrir al-Sham (HTS), has assumed control of Damascus, saying they have no intention of using chemical weapons and will cooperate with the OPCW to ensure its destruction. However, experts warn of the risk of looting and proliferation amid the chaos.
In response, the OPCW held an emergency meeting at its headquarters in The Hague. Its general director, Fernando Arias, stated that the organization is better prepared than 11 years ago to face this challenge, and that they will send teams to Syria as soon as possible.
Meanwhile, Israel has opted for a more direct strategy. The Israel Defense Force (IDF) has carried out multiple airstrikes in recent days against military research centers and suspected chemical warehouses, in a pre-emptive attempt to eliminate any remaining arsenal.
For its part, the Pentagon has expressed concern, although it has not deployed personnel to search for weapons. “We are focused on ensuring that chemical weapons do not fall into the wrong hands”stated spokesperson Sabrina Singh.
The future of chemical weapons in Syria remains uncertain. While some experts rule out the country’s ability to rebuild its former large-scale chemical program, they fear the discovery of hidden materials or chemical-laden munitions that the regime may have tried to hide before its fall.
“What we know is that there is a real risk of proliferationand we cannot afford to wait for someone else to take control of these weapons,” warned a European diplomat who requested anonymity due to the sensitivity of the issue.
