Russian hackers reportedly obtained some of President Obama’s emails when the White House’s unclassified computer system was hacked last year, indicating that the breach was significantly more intrusive than originally thought.

Citing officials briefed on the investigation, The New York Times reported Saturday that while the hackers did not appear to have breached more carefully guarded servers that contain Obama’s BlackBerry messages, they did manage to obtain access to email archives of people with whom Obama communicated.

Officials did not tell The Times how many emails were obtained, but admitted that the unclassified system often contains highly sensitive information that includes schedules, email exchanges with ambassadors and diplomats, and debates about policy and legislation. The president’s email account itself does not appear to have been hacked

No classified networks were compromised and hackers obtained no classified information, White House officials said. Many administration officials have two computers in their offices, one of which operates on a secure network and another unit connected to the outside world for unclassified information.

That Obama’s emails were obtained by Russian hackers in particular – presumed to be linked to the Russian government – caused the intrusion to be seen as so serious that officials met on a nearly daily basis for several weeks afterwards, The Times reported.

“It’s the Russian angle to this that’s particularly worrisome,” a senior US official told The Times.

While the White House is hit by daily cyber attacks, primarily from Russia and China, the hacking occurred at a time of renewed tension with Russia, particularly over the crisis in Ukraine and Russia's military patrols in Europe.

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