U.S. National Security Adviser Jake Sullivan speaks during a press briefing at the White House in Washington, D.C., U.S., Nov. 13, 2024. Reuters-Yonhap

U.S. National Security Advisor Jake Sullivan Friday portrayed impeached President Yoon Suk Yeol's botched martial law bid as "shocking" and "wrong," Friday, but voiced confidence that "structurally," the South Korea-U.S. alliance is "incredibly healthy."

Speaking in a press meeting, he also noted that the Biden administration was not able to make "substantial" progress in the efforts toward the denuclearization of the Korean Peninsula with the security trend moving in the "wrong" direction, but stressed America and its allies are in a "materially better" position to deter North Korean threats.

He also expressed concerns over the "risk" of North Korea using the ongoing political turmoil in South Korea to engage in provocative activities, but underscored that Pyongyang "should make no mistake" given the strength of the bilateral alliance.

"I think the declaration of martial law in early December was shocking. I think it was wrong, and now we are watching a constitutional procedure play out. We want to make sure that it does so without violence, that it does so in accordance with the ROK Constitution," Sullivan said, using the acronym for South Korea's official name, the Republic of Korea.

"I believe that the ROK will come out the other side of this with strong democratic institutions, with a continued deep commitment to the U.S.-ROK alliance," he added.

South Korea has been thrust into a period of political uncertainty following Yoon's short-lived martial law declaration, Dec. 3, and his subsequent impeachment, Dec. 14.

The official painted a sanguine outlook for the Seoul-Washington alliance.

"I think structurally, when you look out over the long term, the U.S.-ROK alliance is incredibly healthy, and that's for deep, fundamental reasons, and that is also because of the cultivation of these past four years," he said.

"I don't know where the new team will take that alliance, but I think it is still very much set up for success, notwithstanding what's happening in terms of the political turmoil inside the ROK."

On North Korea, he admitted to the absence of visible headway in long-elusive endeavors to denuclearize the recalcitrant regime.

"We, like our predecessors, going back to Clinton, we're obviously not able to make substantial progress on the issue of denuclearization of the Korean peninsula. The trend there continues in the wrong direction, as it has under multiple presidents," he said.

"I didn't come in with particularly optimistic views on what we would be able to accomplish, but that's an area that remains of considerable concern."

However, the top security official pointed to progress in efforts to bolster deterrence against North Korea in tandem with South Korea, Japan and other partners.

"We'll see what the new administration is able to do, but what I do think on the North Korea file is that we put ourselves and our allies in a materially better position to deter and deal with that threat, even if we were not able to directly abate the threat," he said.

Asked about the possibility of the North launching military provocations at a time of political uncertainty in Seoul, Sullivan noted a "risk" of the regime's potential saber-rattling.

"I can't predict exactly what North Korea will do, but I certainly think that's a risk ... It's in the American national security interests that the political crisis there gets resolved in accordance with the ROK Constitution as rapidly as possible," he said.

"But I would just say even today, in the midst of the ongoing political turmoil in the ROK, the U.S.-ROK alliance remains strong, our deterrent remains strong, our resolve remains strong, and North Korea should make no mistake about that."

The launch of an intermediate-range ballistic missile (IRBM) with a claimed hypersonic warhead as payload, at an undisclosed location in North Korea, Jan. 6, is seen in this photo released by the official North Korean Central News Agency (KCNA). EPA-Yonhap

Touching on the seriousness of the North Korean threat, the official said it remains "acute" as it has been under former presidents.

"The North Korean threat when President Obama left was acute. It was acute when President Trump left office. It remains acute today," he said.

He pointed to the growing partnership between Pyongyang and Moscow, and an alignment of Russia, China, North Korea and Iran as "the biggest thing that is distinct from four years ago," while noting he has discussed with the Trump team the North Korea-Russia relationship as something that the incoming administration will have to "contend with."

"My broad view of this is that this alignment is not uniform across those countries, and we shouldn't think of it as a single bloc at this point, and we have already taken steps to try to find gaps and seams in it, and I think the next administration should not treat it as a single, unified bloc," he said.

"Second, this alignment is not emerging because of the strength of our competitors and adversaries, but largely because of their weakness and the pressure they are under, and that doesn't mean it's not threatening, but we should honestly assess that these countries are looking to one another because they don't have a lot of other choices."

Highlighting that the Biden administration's Indo-Pacific strategy -- designed to beef up a network of U.S. alliances and partnerships to confront shared challenges -- is working in a "big" way, Sullivan expressed hope that there would be policy continuity under the incoming administration.

"I hope that they will carry it forward. And as I said, if you look at prominent Republican voices, this is an area where I think there's more convergence than there is debate or critique," he said. "So that gives me some hope that there will be this kind of continuity." (Yonhap)