SEOUL, South Korea -- President Barack Obama is "recklessly" spreading rumours of a Pyongyang-orchestrated cyberattack of Sony Pictures, North Korea says, as it warns of strikes against the White House, Pentagon and "the whole U.S. mainland, that cesspool of terrorism."

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 late Sunday also underscores Pyongyang's sensitivity at a 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 U.S. blames North Korea for the cyberattack that escalated to threats of terror attacks against U.S. 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 broadcast Sunday 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 U.S.

"Our toughest counteraction will be boldly taken against the White House, the Pentagon and the whole U.S. 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 U.S.

North Korea and the U.S., which fought each other in the 1950-53 Korean War, remain technically in a state of war because the conflict ended with an armistice, not a peace treaty. The U.S. stations about 28,500 troops in South Korea to deter aggression from North Korea.

The rivals are locked in an international standoff over the North's nuclear and missile programs and its alleged human rights abuses. In the spring of last year, tension dramatically rose after North Korea issued a string of fiery threats to launch nuclear strikes against Washington and Seoul.