Yoon, on the fourth day of a state visit to mark the 70th anniversary of the US-South Korean alliance, also vowed in a speech to a joint meeting of Congress that South Korea would actively work to safeguard the freedom of the people of Ukraine and support their reconstruction efforts.
He was greeted with a standing ovation and repeated loud cheers in a packed House of Representatives chamber by members of the House and Senate.
Yoon paid tribute to the US sacrifice to defend freedom against communism in the 1950-53 Korean War, and its partnership with Seoul since the end of the war.
"The Korean people rose from the ruins of war to build a thriving nation, and at every step America has stood together with Korea."
Yoon told Congress the alliance must stand united to deter North Korea's "reckless behaviour" and highlighted his efforts towards rapprochement with neighbouring Japan after years of strained relations, by saying:
"Along with close Korea-US coordination, we need to speed up Korea-US-Japan trilateral security cooperation to counter increasing North Korean nuclear threats," Yoon said.
Yoon said the world must not "shy away" from promoting freedom for the North.
Yoon paid tribute to the US sacrifice to defend freedom against communism in the 1950-53 Korean War, as well as the work of 19th-century US missionaries to advance women's status in Korea
He was greeted with a standing ovation and repeated loud cheers in a packed House of Representatives chamber by members of the House and Senate.
Yoon became the seventh South Korean leader to address Congress, underscoring the close relationship between Seoul and Washington.
Blinken requests an encore from Yoon at the State luncheon saying: "Don't let the music die"
Secretary of State Antony Blinken on Thursday offered South Korea's President Yoon Suk Yeol the chance to perform musical diplomacy at the State Department Thursday after Yoon sang 'American Pie' at the White House state dinner the night before.
"Mr President I want you to know that we have two great American musical giants with us today, Herbie Hancock and Diane Reeves. So, if you feel moved to deliver another performance, don't let the music die," Blinken said.
Vice President Kamal Harris spoke of the overall relationship between the US and South Korea, saying, "President Yoon, you campaigned for office on a promise to strengthen the alliance between our nations, and you have delivered."
Reuters