Two recent videos have sought to undermine confidence in the security of the vote.
U.S. intelligence agencies have concluded that Russia is behind a video that appeared on social media this week falsely claiming that Haitians illegally voted multiple times for Vice President Kamala Harris in Georgia.
The U.S. government issued a new warning on Friday, one that followed another video that began circulating a week ago falsely claiming that ballots in Pennsylvania were destroyed.
Officials say foreign powers are working to undermine faith in the election, and government agencies in charge of protecting the vote have said the torrent of false claims is greater than before.
The Cybersecurity and Infrastructure Security Agency, the Office of the Director of National Intelligence and the F.B.I. released a joint statement on Friday saying the video was the work of Russia.