"Now more than ever, it is important that we offer our assistance to state and local election officials in the cybersecurity of their systems," Johnson wrote in a .
"Election infrastructure is vital to our national interests, and cyber attacks on this country are becoming more sophisticated, and bad cyber actors—ranging from nation states, cyber criminals and hacktivists—are becoming more sophisticated and dangerous."
Friday's declassified report says that Russian intelligence services "obtained and maintained access to elements of multiple US state or local electoral boards," but went on to conclude that none of the affected systems was involved in vote tallying.
In August, voter registration systems in Arizona and Illinois were reportedly targeted by hackers.
Election officials in Arizona said the FBI warned them the , but they didn't say if the hackers were state-sponsored or financially motivated.