The Slippery Slope of Using Chemical Weapons in Sudan
By: Prof. David M. Crane*
The use of gas in a conflict is prohibited under international law and has been for well over a century. Its use is a war crime, plain and simple. Full stop. The use of chemicals against a belligerent in an armed conflict is rare but not unheard of. It’s been used in the Iraq/Iran war in the 1980s, and the Assad regime in Syria dabbled in its use in the early 21st century. There is also evidence of the use of chemicals by the Russian Federation in Ukraine.
The recent accusations surrounding the alleged use of chlorine gas by the Sudanese army in its conflict with the Rapid Support Forces (RSF) are troubling and must not be ignored. On May 22, 2025, the United States accused the Sudanese military of using chemical weapons. Although they presented no evidence to back their claims, the implications are grave. International law strictly prohibits the use of chemical weapons, and chlorine gas is considered a violation under the Chemical Weapons Convention (CWC), to which Sudan is a signatory.
It's very concerning that chlorine, a substance commonly used in various industries, is reportedly being weaponized. The video evidence documented by the FRANCE 24 Observers team in September 2024, showing barrels dropping from the sky, is particularly alarming. If these claims are substantiated, they mark a dangerous escalation—not just for Sudan but for the principles of international law as a whole.
This pattern—accusations followed by denials from military leaders—is reminiscent of other conflict zones where human rights are disregarded. The Sudanese military’s immediate dismissal of these allegations further obscures the truth and undermines the credibility of international monitoring. The historical context reminds us that the failure to hold violators accountable leads to a dangerous normalization of brutality in warfare. As I’ve previously remarked, “When we allow even the smallest infractions of international law to go unaddressed, we set a precedent that invites further violations.”
The consequences of using chlorine gas as a weapon extend beyond immediate physical harm. They threaten to erode the boundaries that define acceptable conduct in warfare. The very act of using chemical agents introduces a slippery slope, normalizing violence that can lead to more horrific warfare tactics. This hardening stance risks allowing other factions or regimes to follow suit, believing they can operate with impunity.
The international community has a vital role to play right now. It must take these allegations seriously and push for independent investigations into these claims. While the U.S. has made significant assertions, it is essential that any evidence is made public to galvanize an effective global response. The commitment to enforcing the CWC is crucial; violations should prompt not just condemnation but also tangible consequences, such as sanctions or international legal action.
Sudan is at a critical juncture, and what happens next could resonate far beyond its borders. The specter of chemical warfare threatens not only regional stability but also the broader tenets of international law. We can neither afford to turn a blind eye nor allow the unacceptable to become normalized. As a global community, we must remain steadfast in our opposition to the use of chemical weapons, ensuring that those who violate this sacred trust face accountability. It’s not just about Sudan; it’s about the future of warfare and humanity itself.
*Founding Chief Prosecutor, UN Special Court for Sierra Leone; Founder, Global Accountability Network.