Reports Monday say the White House's computer system was targeted in a cyber attack, but a senior administration official also said on Monday that no classified systems were breached.
There is no evidence that data was taken in the incident, the official said, adding that the attack was identified early and did not spread.
The attack was described as "spear phishing," the term for an attempted penetration using fake Emails from a trusted sender, which the official said was "not infrequent."
On Sunday, a report from a news website "Freebeacon," said that Chinese hackers had breached a White House military system.
The White House would not identify the group responsible for the attack, or give specifics when and where it was aimed.
China reportedly has the world's largest Internet user base, at 485 million users, and is believed to be responsible for a number of hacking attacks aimed at the U.S. government and companies.
The Obama administration is preparing to issue an executive order that would direct federal agencies to develop new guidelines to shield computer networks from cyber attacks. The White House undertook the new rules after lawmakers failed this year to pass a comprehensive cybersecurity bill.
