WASHINGTON – Russian forces are deploying an internationally banned choking gas to drive Ukrainian forces from their trenches, the State Department confirmed Thursday.

Moscow has been using the lung-damaging agent Chloropicrin, first created as a poison gas in World War I, in violation of the International Chemical Weapons Convention arms control treaty.

In the case of Russia’s 26-month-old war on Ukraine, the purpose of the gas is to force Kyiv’s forces to break cover so they can be targeted with conventional weapons, such as artillery and gunfire.

This tactic of creating no safe hiding space for adversaries is highly controversial and internationally condemned.

“The use of such chemicals is not an isolated incident,” the State Department said in a statement.

“Pursuant to the [Chemical and Biological Weapons] Act, the Department is re-imposing restrictions on foreign military financing, US Government lines of credit, and export licenses for defense articles and national security-sensitive items going to Russia,” it added.

The State Department is also “sanctioning three Russian government entities associated with Russia’s chemical and biological weapons programs and four Russian companies that have contributed to such entities.”

The US additionally confirmed the Kremlin’s use of tear gas, which is also banned for use in warfare under the Chemical Weapons Convention of 1997, which was ratified by more than 150 countries – including Russia.

However, as the State Department pointed out, Russian President Vladimir Putin has notoriously used chemical weapons outside of global combat zones.

“Russia’s ongoing disregard for its obligations to the CWC comes from the same playbook as its operations to poison Aleksey Navalny and Sergei and Yulia Skripal with Novichok nerve agents,” the agency said.

While US officials, including National Security Council spokesman John Kirby, have previously said Moscow was believed to have used other chemical agents on the battlefield, this week was the first time the State Department publicly confirmed the use of Chloropicrin.

Defense experts have repeatedly drawn comparisons between World War I and the current conflict, with many noting Ukraine’s heavy reliance on trench warfare to contain Russian advances.