WASHINGTON -- South Korean President Yoon Suk Yeol and US Secretary of Defense Lloyd J. Austin III held a meeting at the Pentagon on Thursday to underscore their robust alliance and the unwavering commitment of the United States in supporting South Korea's defense against North Korea's provocative actions.

On his final day in Washington D.C., President Yoon visited the Pentagon before heading to Boston. He is set to deliver a speech at Harvard University's Kennedy School of Government on how to respond to challenges that threaten freedom.

During the meeting at the Pentagon, Defense Secretary Austin told President Yoon that they continue to confront persistent challenges from North Korea, particularly in relation to its hazardous and destabilizing missile testing program. They also discussed the broader issue of countering those who seek to undermine the rules-based international order.

“I want to underscore, Mr. President, what I said in January, that the US commitment to the defense of the ROK is ironclad,” Austin said. “And so is our extended deterrence commitment to your country, which includes a full range of US defense capabilities, including conventional, nuclear and missile defense capabilities.”

In response, Yoon told Austin that he has full confidence in the US commitment to extended deterrence.

“The Korean government -- based on our robust combined defense posture -- we will resolutely and affirmatively respond to North Korean threats,” Yoon said. “Against North Korea's nuclear and missile threats, we will be prepared with our capability for punishment and with our overwhelming response capability, including Korea's three-axis system.”

Yoon promised to step up the nation’s exercises and training as a combined force, and to increase its security cooperation with the US and Japan.

“If North Korea dares to use its nuclear arsenal, it will face a decisive and overwhelming response by the Republic of Korea forces and the alliance, including the US' nuclear capabilities,” Yoon said.

Prior to his visit to the Pentagon, Yoon had a state lunch co-hosted by Vice President Kamala Harris and Secretary of State Tony Blinken.

“Yesterday, President Biden and I had various and beneficial discussions about the direction of the South Korea-US alliance. Based on this, we intend to develop the alliance in a way that expands practical benefits for the people of both countries,” Yoon said at the luncheon held at the US Department of State. “Our future will be more brilliant than the past.”

Later, Yoon visited the US Defense Advanced Research Project Agency where he received a briefing on the agency's overall operation status from Director Stefanie Tompkins. During the visit, he looked around the exhibition at the cutting-edge technologies being researched, planned and supported by DARPA, according to Yoon’s spokesperson, Lee Do-woon, in a written statement.

DARPA is an organization that has led America's high-tech innovation by investing in innovative technologies for national security purposes and developing world-changing technologies such as GPS, stealth, voice recognition, autonomous driving and artificial intelligence technologies.

Yoon said that the ROK's military is currently pushing to make a leap into becoming a science and technology powerhouse through strong defense innovation, and is trying to fundamentally change the military system by incorporating advanced science and technology. Yoon said he hoped that Korean scientists would expand into advanced science and technologies with DARPA.