The new US policy toward North Korea does not affect the United States' alliance with South Korea or its defense commitment on the Korean Peninsula, a Pentagon spokesman said Monday.

John Kirby made the remark when asked if the outcome of the recently concluded North Korea policy review may affect the US defense posture on the Korean Peninsula.

"We also have concomitant alliance requirements on the peninsula with our South Korean allies to continue to make sure we are, as the saying goes, 'ready to fight tonight,' and so that work continues," he said, referring to the slogan of the South Korean and US Combined Forces Command.

"I mean...from the Department of Defense perspective, one thing that hasn't changed is our commitment to the treaty alliance with South Korea," he added in a department press briefing.

On Friday, the White House said the United States will seek "calibrated" and diplomatic ways to make practical progress toward the denuclearization of North Korea, announcing the conclusion of its North Korea policy review that began soon after Joe Biden took office as president on Jan. 20.

In addition to the North Korea policy review, the US is also undertaking a global defense posture review, which has yet to be completed.

Kirby said the US military will support the new US approach to dealing with nuclear-armed North Korea.

"As I said, whatever the outreach looks like to help with denuclearization of North Korea, the (defense) department will support that," he said.

The US earlier said it has sought to engage with North Korea since mid-February but that Pyongyang remained unresponsive.

On Sunday (Seoul time), the North warned the US will face "worse and worse crisis" down the road, accusing Biden of making a "big blunder" against its leader, Kim Jong-un, in his recent address to Congress, where he vowed to work with US allies to denuclearize the North through "diplomacy, as well as deterrence."

"We stand in support of the State Department as they pursue peaceful, political, diplomatic options to make the region safer and more secure, and that includes making it safer and more secure from the threat that North Korea continues to pose," said Kirby.

The US currently maintains some 28,500 troops on the Korean Peninsula. (Yonhap)