The White House said on Friday that the threat by the Democratic People's Republic of Korea (DPRK) to launch rocket attack on the United States only deepened its isolation.

"The bellicose rhetoric emanating from North Korea only deepens that nation's isolation," said White House spokesman Josh Earnest in a briefing.

"The United States remains committed to safeguarding our allies in the region and our interests that are located there as well," he told reporters.

Kim Jong Un, the top leader of the DPRK, has ratified a strike plan by the Strategic Rocket Force as the U.S. B-2 stealth bombers flew over the Korean Peninsula, the KCNA, DPRK's official new agency, reported Friday.

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

In the briefing, Earnest reiterated Washington's conditions for the DPRK to return to the international community.

"They need to end the provocative acts and the bellicose rhetoric. They need to abandon their nuclear program. They need to live up to their international obligations," said Earnest. "That would, of course, require the regime to put the interest of their people first; to focus on their well-being, their ability to have access to food and medicine."

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 Republic of Korea.

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