U.S. intelligence officials said Monday they were confident that Iran was responsible for the hack of Donald Trump's presidential campaign, casting the cyber intrusion as part of a brazen and broader effort by Tehran to interfere in American politics and potentially shape the outcome of the election.

The assessment from the FBI and other federal agencies was the first time the U.S. government has assigned blame for hacks that have raised anew the threat of foreign election interference and underscored how Iran, in addition to more sophisticated adversaries like Russia and China, remains a top concern. Besides breaching the Trump campaign, officials also believe that Iran tried to hack into the presidential campaign of Kamala Harris.