It would be “unwise” for the Syrian regime of Bashar al-Assad to deploy chemical weapons against civilians, the United States Secretary of Defense James Mattis told reporters as he traveled to Oman.

Mattis said, “We have made it very clear that it would be very unwise to use gas against people, civilians, on any battlefield.”

While chlorine is not a banned weapon, its use in war is prohibited. Mattis said that if someone in the vicinity of an explosion has trouble breathing and if the area near the explosion is dusty for a while afterward, it is a sign of a chlorine attack. After making those observations he reiterated that it would be “very unwise” for the Assad regime to use “weaponized gas.” The defense secretary also said that President Donald Trump “made that very clear early in his administration.”

In April of last year, the U.S. launched cruise missiles at a Syrian airbase following a chemical weapons attack with the deadly nerve agent, sarin, in northern Syria. Subsequent reports of chemical weapons, including during the recent assault by the regime on Eastern Ghouta, have not provoked any American response. Mattis said that Trump had “full political maneuver room” to decide on a response to Syria’s use of deadly chemicals.

Mattis also criticized Russia, which had guaranteed the 2014 deal that forestalled an attack on Syria by guaranteeing the removal of all of its chemical weapons. Russia, the secretary said, “again, either Russia is incompetent or in cahoots with Assad,” for allowing Assad to keep some of his chemical weapon stockpile.

The defense secretary also downplayed Russian claims of having improved its military capabilities. Saying that he was “paid to make strategic assessments,” Mattis declared that he “saw no change to the Russian military capability.”

[Photo: Department of Defense]