Chinese hackers were able to access the White House Military Office.
According to the Washington Free Beacon, defence and intelligence officials familiar with the incident said that the breach was one of Beijing's most brazen cyber attacks against the United States, and highlights a failure of the Obama administration to press China on its persistent cyber attacks.
An Obama administration national security official said that this ‘"was a spear phishing attack against an unclassified network" and confirmed that the type of attack was ‘not infrequent' and that there were unspecified mitigation measures in place.
The report claimed that US officials familiar with reports of the White House hacking incident said it took place earlier this month and involved unidentified hackers who were believed to have used computer servers in China and accessed the computer network used by the White House Military Office (WHMO).
This network is the US president's military office in charge of some of the government's most sensitive communications, including strategic nuclear commands. The office also arranges presidential communications and travel, and inter-government teleconferences involving senior policy and intelligence officials.
The official said: “In this instance the attack was identified, the system was isolated, and there is no indication whatsoever that any exfiltration of data took place.”
They also said that security officials are investigating the breach and have not yet determined the damage that may have been caused by the incident.
A White House spokesperson had no immediate comment on the cyber attack, or on whether President Obama was notified of the incident.