North Korea is warning of strikes against the White House, Pentagon and "the whole US mainland, that cesspool of terrorism".

It has also accused President Barack Obama of "recklessly" spreading rumours of a Pyongyang-orchestrated cyberattack of Sony Pictures.

Such rhetoric is routine from North Korea's massive propaganda machine during times of high tension with Washington.

But a long statement from the powerful National Defence Commission also underscores Pyongyang's sensitivity at a parody movie whose plot focuses on the assassination of its leader Kim Jong Un, who is the beneficiary of a decades-long cult of personality built around his family dynasty.

The US blames North Korea for the cyberattack that escalated to threats of terror attacks against US movie theatres and caused Sony to cancel The Interview's release.

Obama, who promised to respond "proportionately" to the attack, told CNN's State of the Union in an interview that Washington is reviewing whether to put North Korea back on its list of state sponsors of terrorism.

The National Defence Commission, led by Kim, warned that its 1.2 million-member army is ready to use all types of warfare against the US.

"Our toughest counteraction will be boldly taken against the White House, the Pentagon and the whole US mainland, the cesspool of terrorism, by far surpassing the 'symmetric counteraction' declared by Obama," said the commission's Policy Department in a statement carried by the official Korean Central News Agency.

North Korea has said it knows how to prove it had nothing to do with the hacking and proposed a joint investigation with the US.