WASHINGTON (AP) -- The Justice Department is preparing criminal charges in connection with an Iranian hack that targeted Donald Trump's presidential campaign in a bid to shape the outcome of the November election, two people familiar with the matter said Thursday.

It was not immediately clear when the charges might be announced or whom precisely they will target, but they are the result of an FBI investigation into an intrusion that investigators across multiple agencies quickly linked to an Iranian effort to influence American politics.

The prospect of criminal charges comes as the Justice Department has raised alarms about aggressive efforts by countries including Russia and Iran to meddle in the presidential election between Trump and Democratic nominee Kamala Harris, including by hacking and covert social media campaigns designed to shape public opinion.

Iran "is making a greater effort to influence this year's election than it has in prior election cycles and that Iranian activity is growing increasingly aggressive as this election nears," Assistant Attorney General Matthew Olsen, the Justice Department's top national security official, said in a speech Thursday in New York City.

"Iran perceives this year's elections to be particularly consequential in impacting Iran's national security interests, increasing Tehran's inclination to try to shape the outcome," he added.

The Trump campaign disclosed on Aug. 10 that it had been hacked and said Iranian actors had stolen and distributed sensitive internal documents. At least three news outlets -- Politico, The New York Times and The Washington Post -- were leaked confidential material from inside the Trump campaign. So far, each has refused to reveal any details about what it received.

Politico reported that it began receiving emails on July 22 from an anonymous account. The source -- an AOL email account identified only as "Robert" -- passed along what appeared to be a research dossier that the campaign had apparently done on the Republican vice presidential nominee, Ohio Sen. JD Vance. The document was dated Feb. 23, almost five months before Trump selected Vance as his running mate.

The FBI, the office of the Director of National Intelligence and the Cybersecurity and Infrastructure Security Agency subsequently blamed that hack, as well as an attempted breach of the Biden-Harris campaign, on Iran.

Those agencies issued a statement saying that the hacking and similar activities were meant to sow discord, exploit divisions within American society and influence the outcome of elections.

The statement did not identify whether Iran has a preferred candidate, though Tehran has long appeared determined to seek retaliation for a 2020 strike Trump ordered as president that killed an Iranian general.

The two people who discussed the looming criminal charges spoke on condition of anonymity to The Associated Press because they were not authorized to speak publicly about a case that had not yet been unsealed.

The Washington Post first reported that charges were being prepared.

Justice Department officials have been working to publicly call out and counter election interference efforts. The response is a contrast to 2016, when Obama administration officials were far more circumspect about Russian interference they were watching that was designed to boost Trump's campaign.

"We have learned that transparency about what we are seeing is critical," Olsen, the Justice Department official, said Thursday.

"It helps ensure that our citizens are aware of the attempts of foreign government to sow discord and spread falsehoods -- all of which promotes resilience within our electorate," he added. "It provides warnings to our private sector so they can better protect their networks. And it sends an unmistakable message to our adversaries -- we've gained insight into your networks, we know what you're doing, and we are determined to hold you accountable."

Last week, in an effort to combat disinformation ahead of the election, the Justice Department charged two employees of RT, a Russian state media company, with covertly funneling a Tennessee-based content creation company nearly $10 million to publish English-language videos on social media platforms with messages in favor of the Russia government's interests and agenda.