Russian President Vladimir Putin said Tuesday that U.S. elections have been falsified through mail-in voting.

“In the United States, previous elections were falsified through postal voting … they bought ballots for $10, filled them out, and threw them into mailboxes without any supervision from observers, and that’s it,” Putin said, according to Reuters.

Putin, who is running for reelection in Russia, did not offer evidence to back his claims, Reuters reported.