A published report says Russian hackers who penetrated White House cybersecurity last year read some of President Barack Obama's unclassified emails.
Saturday's New York Times report said the hackers, who also accessed the State Department's unclassified system, did not appear to have penetrated closely guarded servers that control message traffic from the president's BlackBerry. Either Obama or an aid carries that device at all times.
But the report said hackers did gain access to email archives of people inside the White House with whom the president regularly communicated. From those accounts, the report said, intruders reached emails the president had sent and received.
The White House confirmed the breach this month, saying that it took place last year.
Many senior officials operate two official computers, one running on a highly secure network and the other connected to the outside world for unclassified communications.
Authorities have not yet disclosed the number of the president's compromised emails.
But authorities have conceded that the unclassified system routinely contains sensitive information, including schedules and communications with ambassadors and diplomats.
The unclassified systems are also said to contain communications on legislation and policy debates.