A White House official says President Joe Biden and his South Korean counterpart Yoon Suk-yeol will reaffirm the United States' extended deterrence against North Korea when they meet on Wednesday.

Yoon arrived in Washington on Monday. He is the first South Korean president in 12 years to pay a state visit to the US.

US National Security Advisor Jake Sullivan told reporters on Monday that the two leaders will release a statement that deals with the question of extended deterrence, particularly in the context of the threat posed by North Korea.

Sullivan said the statement will send a "very clear and demonstrable signal of the United States' credibility" when it comes to its commitments to South Korea and its people.

Extended deterrence refers to the US commitment to defend its allies with its conventional and nuclear capabilities. Washington and Seoul are marking the 70th anniversary of their alliance this year.

Sullivan's remarks suggest that the two presidents will reaffirm the strength of their alliance in an effort to brush aside doubts raised by some South Koreans over the US nuclear deterrence against the North.

Sullivan said Biden and Yoon are also expected to discuss assistance to Ukraine, cybersecurity and Taiwan during their meeting.