Moscow has regularly charged that Washington provides cover, if not all-out support, for militant forces fighting against Syria’s regime and civilian population. Its latest effort backfired last month when Russia’s Defense Ministry attached video game footage as “irrefutable evidence” of its claims.

Russia has once again accused the United States of training terrorists in Syria, this time at a military base in the south of the war-torn country.

“According to space and other types of surveillance data, there are militant units [inside a U.S. base in Tanf, Syria]. They are, in fact, training there,” General Valery Gerasimov, Chief of the General Staff of Russia's Armed Forces, said in an interview with the Komsomolskaya Pravda tabloid on Wednesday.

Gerasimov cited a BBC report about a secret U.S.-led coalition deal to let hundreds of Islamic State (IS) fighters escape their former stronghold of Raqqa in October. He estimated around 350 of these fighters were in the Tanf base in southern Syria and 750 more at another base in a Kurdish-held region in the northeast.

“They are de-facto IS. But, after they are worked on, they change colors and rename themselves the ‘New Syrian Army,’ or otherwise,” Gerasimov said.

The U.S. has not yet responded to Russia’s latest accusations.

IS is a terrorist organization banned in Russia.