Opinion editor's note: Editorials represent the opinions of the Star Tribune Editorial Board, which operates independently from the newsroom.

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State dinners are usually staid affairs, unlikely to result in a viral video. But the one held last week for Yoon Suk Yeol was the exception after the South Korean president crooned one of his favorite songs, "American Pie."

The musical interlude seemed fitting, given the harmony projected during meetings and the dinner with President Joe Biden, as well as Yoon's well-delivered and well-received address to a joint session of Congress. Despite some discordant notes — particularly after the "Discord Leaks" revealed U.S. surveillance of its Korean allies — the now 70-year bilateral relationship between the U.S. and South Korea is strong.

And given events on the Korean Peninsula and the broader geopolitical challenge of China's rise, it needs to remain so.

That's because North Korea shows no sign of relinquishing its nuclear arsenal. In fact, it's adding to it, along with a ballistic missile program that presents an evermore lethal threat to South Korea, Japan and even the continental United States.

China, North Korea's enabling ally, has its leverage over North Korea but won't use it. And Pyongyang seems to be solidifying its relationships with other authoritarian capitals, including Moscow. Not surprisingly, that's led many South Koreans — including, for a bit, Yoon himself — to openly question whether their nation should abrogate its inclusion in the Nuclear Nonproliferation Treaty and develop its own nuclear arsenal.

Yoon has wisely declined this route, and his stance is now bolstered by Biden's announcement of the "Washington Declaration," which includes "the establishment of a new Nuclear Consultative Group (NCG) to strengthen extended deterrence, discuss nuclear and strategic planning, and manage the threat to the nonproliferation regime posed by the Democratic People's Republic of Korea," in effect giving Seoul more say in planning for any nuclear contingency — although it's clear that any decision on deploying nuclear weapons would remain with Washington.

In addition, as part of America's renewed commitment to the U.S.-ROK Mutual Defense Treaty, the U.S. has agreed to intermittently dock nuclear-armed submarines in South Korea for the first time in about 40 years. Joint-military exercises will increase, too. Biden bolstered these moves rhetorically by stating that "a nuclear attack by North Korea against the United States or its allies and partners is unacceptable and will result in the end of whatever regime were to take such an action."

The Washington Declaration "was really a move on the part of the U.S. to bring further assurance to South Korea — and, honestly, the region as a whole — that the U.S. extended deterrence, the U.S. nuclear umbrella, is just as strong as it's always been," Lauren D. Gilbert, associate director at the Atlantic Council's Indo-Pacific Security Initiative, told an editorial writer. It's "a way of saying that even if South Korea doesn't have its own nuclear weapons, the U.S. is there and ready to defend."

U.S. policy should continue to pursue the denuclearization of North Korea. But the U.S. and its Asian allies must be realistic that Pyongyang's dynastic dictatorship does not intend to use its arsenal as a bargaining chip but as a way to ensure the regime's survival. By clearly stating the stakes and even bringing nuclear weapons in closer proximity, it sends an unmistakable message to the North while defusing the political and public pressure in the South to proliferate.

Gilbert's reference to "the region as a whole" reflects the broader context of the challenge of a rising and more bellicose China. That's one of the factors in recent diplomatic breakthroughs between Seoul and Tokyo after years of strained relations over World War II "history issues" like forced labor and "comfort women." Yoon deserves great credit for the détente, which will lead to a more cohesive and thus effective front on security issues that only seem to be intensifying.

"At 70 years, we're definitely seeing continued strength in the alliance," Gilbert said. But, she added, "It's becoming more of a fully comprehensive relationship, rather than one focused purely on the military and defense aspect."

Indeed, while challenges will continue, as with any alliance, there's much that bonds the U.S. and South Korea beyond security concerns, including a commitment to democracy, integrated economies, and, increasingly, cultures, including hit Korean films, TV shows and music (from K-pop, not Korea's president), all of which bode well for the next 70 years of partnership and friendship.