A US B-2 stealth bomber (right) flies over a US air base in Pyeongtaek, south of Seoul, on Thursday, as part of a ROK-US joint military exercise. [Photo/Agencies]

PYONGYANG - Top leader of the Democratic People's Republic of Korea (DPRK) has ratified a strike plan by the Strategic Rocket Force as US B-2 stealth bombers flew over the Korean Peninsula, the KCNA news agency reported Friday.

"The time has come to settle accounts with the US imperialists in view of the prevailing situation" Kim Jong-un was quoted as saying after an urgent meeting with top military officials early Friday.

He ratified a plan of the Strategic Rocket Force for firepower strike on the US mainland, Hawaii and Guam, and the Republic of Korea if they "make a reckless provocation", said the KCNA.

Kim said the latest US move is "not a simple demonstration of forces" but "an ultimatum that will ignite a nuclear war at any cost on the Korean Peninsula".

Two B-2 Spirit bombers were sent to the Korean Peninsula Thursday for a firing drill but US Defense Secretary Chuck Hagel denied that flying the bombers to the peninsula would aggravate the situation in the region.

Tensions have been running high on the Korean Peninsula since the DPRK conducted its third nuclear test on Feb 12 as a countermeasure against the joint military drills of the United States and the ROK.

The DPRK also threatened to launch a preemptive nuclear strike for self-defense and unilaterally nullified the 1953 armistice that suspended the Korean War.