US National Security Advisor Jake Sullivan on Tuesday expressed worries about North Korean threats and other challenges, but stressed US allies and partners would only close ranks in the face of the challenges.

Sullivan made the remarks at the World Economic Forum in Davos, Switzerland, touching on a series of global challenges, including Russia's war in Ukraine, the war between Israel and the Hamas militant group and Houthi attacks in the Red Sea.

"My job is to worry about the things I talked about today ... but (I) also worry about other threats too, like North Korea," he said as he explained US efforts to tackle the threats.

But, Sullivan said he remains "optimistic" as he pointed to the US' close-knit network of allies that the Joe Biden administration has called "great strategic assets."

"The more others seek to undermine the international system through violence and coercion, the more it brings our allies and partners closer together," he said. "This is the paradox that leaders like Putin cannot seem to resolve."

He also voiced confidence that the America-led "model" that "delivers for people" will remain much more attractive globally than "that of aggression, coercion, intimidation or confrontation."

"When it comes to world politics, people around this planet are much more interested in whether or not their lives are improving than in anyone's imperial ambition or imperial project," he said.

Commenting on the heightened tensions in the Red Sea, Sullivan said that the United States is not looking for regional conflict.

"Through a combination of steady deterrence and steadfast diplomacy, we seek to stop the spread of conflict and to create the conditions for de-escalation," he said. "Our approach remains focused on moving towards greater integration and stability in the region." (Yonhap)