A senior White House official on Thursday called for strengthened U.S. extended deterrence for South Korea and Japan amid challenges in the Indo-Pacific region posed by North Korea's nuclear threat.

Kurt Campbell, the White House National Security Council coordinator for Indo-Pacific affairs, made the remark at a security forum hosted by the Aspen Institute, a think tank based in Washington.

Asked about growing calls for nuclear armament within South Korea, Campbell said that one of the enormous achievements in the Indo-Pacific for decades has been the stability and reassuring quality of the U.S.’ extended deterrence with its nuclear umbrella.

Campbell said that many countries in Asia with the potential to possess their nuclear weapons have opted not to, instead relying on the strength and predictability of the U.S.’ extended deterrence, which is being challenged now.

The official said a major challenge is coming from Pyongyang’s nuclear threats, particularly the prospect of a seventh nuclear test, adding that the North’s behavior and threats are undermining security and raising concerns in Northeast Asia.

He said that Russia's public threat to use nuclear weapons in Ukraine and China's efforts to bolster its nuclear capabilities are also prompting calls for nuclear armament in other countries.

The official stressed that the U.S. should make it clear to Japan, South Korea and other countries that the U.S. nuclear deterrent remains robust and the commitment to such deterrence in the Indo-Pacific is unequivocal.