Andrii Derkach, a member of Ukraine’s legislature who has worked with Rudy Giuliani to attack Joe Biden, is “an active Russian agent” seeking to interfere in the 2020 presidential campaign, according to U.S. officials.

“Andrii Derkach and other Russian agents employ manipulation and deceit to attempt to influence elections in the United States and elsewhere around the world,” Treasury Secretary Steven Mnuchin said Thursday. “The United States will continue to use all the tools at its disposal to counter these Russian disinformation campaigns and uphold the integrity of our election system.”