South Korean and US officials on Wednesday expressed strong confidence over the present and future of the two countries' evolving alliance, calling it "ironclad" and "unwavering," as they celebrated the Korean National Day and Armed Forces Day in Washington on Wednesday.

Their paean for the decadesold alliance came as Seoul and Washington have been stepping up security cooperation amid a series of regional and global security challenges, including North Korea's evolving nuclear and missile threats, conflicts in the Middle East and Russia's protracted war in Ukraine.

The celebration was attended by some 1,500 people, including South Korean Ambassador to the United States Cho Hyun-dong, Congressman Don Beyer, US Secretary of the Navy Carlos Del Toro and Acting Under Secretary of State for Political Affairs John Bass.

The event's venue, the Andrew W. Mellon Auditorium, drew particular attention as it was where the North Atlantic Treaty was signed in 1949 by representatives of 12 founding member countries to create the transatlantic alliance during the Cold War.

"NATO's 75th anniversary celebration was also just hosted right here in July, but tonight, we are here to celebrate a different, critical and long-standing alliance," Cho said. "Over the last 71 years, the Korea-US alliance has united our shared values and visions to become a global comprehensive strategic alliance." (Yonhap)

Cho stressed that the future of the South Korea-US alliance stands on three interconnected pillars -- thriving economic cooperation, strong security cooperation and people-to-people ties.

In particular, the ambassador said that the bilateral partnership has been upgraded to a "nuclear-based" alliance, as he pointed to the Washington Declaration that President Yoon Suk Yeol and US President Joe Biden issued in April last year to strengthen the credibility of America's nuclear umbrella.

The declaration involved the establishment of the allies' Nuclear Consultative Group, which Cho said ensures the two countries are prepared for "any kind of nuclear contingencies."

Rep. Beyer underscored the importance of cooperation between Seoul and Washington in tackling shared challenges.

"We are partners to an unprecedented degree," he said. "South Korea is a critical and increasingly important partner in the most pressing challenges both of our nations face for managing relations with North Korea to ... peace and stability in the Taiwan Strait and in confronting the aggression of Russia in Ukraine."

He touted South Korean businesses' activities in the US, including their investments, and expressed his hope for the inflow of highly skilled Korean workers into the US

"We have a real worker shortage here," he said. "If we can help take those wonderful high-tech Koreans, we would love to have them make their home here."

The congressman also voiced his wish for America to leverage South Korea's shipbuilding capabilities to meet its needs, stressing that it will be a "win-win for everyone."

The Navy secretary underlined the strength of the alliance that he said is built on the shared principles of freedom, democracy and the rule-based order.

"The Republic of Korea is not only a symbol of freedom, but also a symbol of resilience against authoritarianism and a beacon of hope around the world," he said.

He struck a sanguine note on the future of the bilateral relationship.

"It is my sincere hope that the partnership between Korea and the US continues to grow, especially amidst the uncertainty and the challenges we face today," he said.

Ambassador Bass cast the two countries' defense ties as "ironclad" and "unwavering."

"This alliance stands as a bulwark against the threats of dictators and authoritarianism in the immediate region and around the world," he said. "Likewise, our two countries are working together to defend and promote our shared values, to address the climate crisis and to produce and secure the technologies of the future."

He also pointed out growing cultural exchanges and people-to-people ties between the two nations.

"Ten percent of Netflix global catalogue is now Korean content," he said. "Our people-to-people ties are also a critical pillar of our alliance," he said.

Also present at the celebration were a group of South Korean veterans who fought alongside US and other U.N. forces during the 1950-53 Korean War -- a conflict that ended in a truce rather than a permanent peace treaty.