Russia appears to be the source of a hack into the Hillary Clinton campaign's computer system — the same intelligence agency behind the recent cyberattack on the Democratic Congressional Campaign Committee, a law enforcement official said Friday.
"It's the same adversary," the official told The New York Times. "These are sophisticated actors."
The Democratic group, which raises money for those running for the House, experienced an attack from a group known as "Fancy Bear," the Times reports.
The entity is connected to the GRU, Russia's military intelligence service, an official involved in the forensic investigation said.
That operation was linked to the hack last month on the Democratic National Committee, which led to the release of thousands of internal emails by WikiLeaks and to the resignation of the committee's chairwoman, Debbie Wasserman Schultz, before the party's convention in Philadelphia this week.
The cyberattack on the House fundraising group was reported Thursday.
That breach may have occurred from June 19 to June 27, though it may have been longer, according to analysis conducted by U.S. network security company FireEye, Reuters reports.
The Justice Department's national security division was investigating whether the attacks threatened national security, according to Reuters.
That the department's national security division was involved indicated that the Obama administration had concluded that the hacking was state-sponsored.
The FBI told the Times Friday that it was investigating reports of "cyberintrusions involving multiple political entities" but did not identify which targets were attacked.
The agency said that it was "aware of media reporting on cyberintrusions involving multiple political entities, and is working to determine the accuracy, nature and scope of these matters.
"The cyberthreat environment continues to evolve as cyberactors target all sectors and their data. The FBI takes seriously any allegations of intrusions, and we will continue to hold accountable those who pose a threat in cyberspace."
Nick Merrill, a spokesman for the Clinton campaign, said that "an analytics data program maintained by the DNC, and used by our campaign and a number of other entities, was accessed as part of the DNC hack.
"Our campaign computer system has been under review by outside cybersecurity experts," he said in a statement. "To date, they have found no evidence that our internal systems have been compromised."
The Clinton campaign's analytics program that was breached involved voter analysis and targeting, the Times reports.
The intrusion was apparently discovered by private investigators hired by the Clinton campaign, CNN reports.
Meredith Kelly, a spokeswoman for the DCCC, said that the committee had hired cyber security firm CrowdStrike to investigate.
"We have taken and are continuing to take steps to enhance the security of our network," she said. "We are cooperating with federal law enforcement with respect to their ongoing investigation."
Yahoo News reported Friday that the FBI warned the Clinton campaign in March that it was the target of a cyberattack, but the agency was rebuffed as it tried to investigate.
The agency sought logs and contact information for its inquiry, but the campaign determined that the queries for such sensitive materials would be too intrusive.
California Sen. Dianne Feinstein said Friday that "it wouldn't surprise me" that the Clinton campaign was hacked.
"It should be pretty clear that both campaigns should be aware that there's a problem out there," Feinstein, a longstanding member of the Senate Intelligence Committee, told Wolf Blitzer on CNN. "Until the technical people can come up with some solutions, which are more ironclad … everybody should be cautious."
Clinton campaign officials have suggested that Russian President Vladimir Putin is trying to influence the outcome of the November election in favor of Republican Donald Trump, though it has admitted to lacking evidence to support the claim.
Operatives for Trump, who has expressed admiration for Putin, have dismissed the accusations.
The developer came under intense fire for calling on Russia on Wednesday to find Clinton's missing emails from her private server, which Trump later said was sarcasm.
Speaking at the Aspen Security Forum in Colorado on Friday, CIA Director John Brennan would not speak to the specific allegations of the Clinton campaign, but told the Times that "obviously, interference in the U.S. election process is a very, very serious matter — and I think certainly this government would treat it with great seriousness."