The information the U.S. showed Moscow trying to prove that the Syrian regime was behind an alleged chemical weapons attack is “absolutely unconvincing,” Russia’s foreign minister said Monday.

The United States insists Syrian President Bashar Assad’s troops were behind the chemical attack on Aug. 21, which they say killed over 1,400 people, and is considering strikes against his regime. Moscow is Assad’s key ally and weapons supplier, and its protector at the United Nations.

Speaking at Russia’s top diplomatic school, Sergey Lavrov said the evidence Washington presented was not detailed.

“Yes, they showed us some findings but there was nothing specific there: no geographic coordinates, no names, no proof that the tests were carried out by the professionals,” Lavrov said. He did not say what tests he was referring to.

“What our American, British and French partners showed us in the past and have showed just recently is absolutely unconvincing,” Lavrov said. “And when you ask for more detailed proof they say all of this is classified so we cannot show this to you.”

(AP)