Unnamed sources insisting on anonymity told the Post that the hacks were into “unclassified” networks and that there’s no evidence that classified computers had been compromised.
A White Office official said that admins noted the activities straight away meaning there was some disruption to web services.
The National Security Agency (NSA), the FBI and the Secret Service have been invoked to assist with inquiries into the hackers.
The Russian government has not, so far, commented on the alleged intrusion. But it’s thought that hackers have targeted computers at NATO, official Ukraine sites, and companies supplying the US defence with kit.
The White House said that people try to hack US computers on a regular basis but the country has a military wing called US Cyber Command which can defend – or attack – intruders.