Iran Is to Blame for Hacking Into Trump’s Campaign, Intelligence Officials Say

American intelligence agencies said on Monday that Iran was responsible for hacking into former President Donald J. Trump’s campaign and trying to breach the Biden-Harris campaign.

The finding, which was widely expected, came days after a longtime Trump adviser, Roger J. Stone, revealed that his Hotmail and Gmail accounts had been compromised. That intrusion evidently allowed Iranian hackers to impersonate him and gain access to the emails of campaign aides.

The announcement was the starkest indication to date that foreign intelligence organizations have mobilized to interfere in the 2024 election at a moment of heightened partisan polarization at home and escalating tensions abroad between Iran and Israel, along with its international allies, including the United States.

“Iran seeks to stoke discord and undermine confidence in our democratic institutions,” intelligence officials wrote in a joint statement from the F.B.I., the Office of the Director of National Intelligence and the Cybersecurity and Infrastructure Security Agency.

The Islamic Republic has “demonstrated a longstanding interest in exploiting societal tensions through various means,” the officials added.

The joint statement provided no new details about the attacks, nor did it specify how the agencies knew Iran was responsible.