The United States on Monday accused Iran of launching cyber operations against the campaigns of both U.S. presidential candidates and targeting the American public with influence operations aimed at fanning political discord.

"We have observed increasingly aggressive Iranian activity during this election cycle," said a statement from the FBI, the Office of the Director of National Intelligence and the Cybersecurity and Infrastructure Security Agency, which oversees the defense of government computer systems.

The statement confirmed charges made earlier this month by the campaign of Republican presidential nominee Donald Trump that Iran hacked one of its websites, triggering an FBI investigation.