US President Joe Biden and South Korean President Yoon Suk-yeol held talks at the White House on Wednesday.

At the start of their meeting, Biden said the two countries are "doubling down on" cooperation as allies, even as North Korea "ramps up its challenges."

He said Yoon's "courageous" diplomacy to improve ties with Japan has strengthened the relationship among the three countries and "makes an enormous difference."

Yoon said the summit is a milestone as the South Korea-US alliance advances as a global alliance aiming to realize global peace and prosperity.

The two leaders likely discussed the concept of extended deterrence amid the acceleration of North Korea's nuclear and missile development.

Extended deterrence refers to Washington's commitment to defend US allies with its military power, including nuclear weapons.

A high-ranking US official said on Tuesday that Biden and Yoon will issue what will be called the "Washington Declaration," setting out how they will prepare for unpredictable events. The official said the declaration calls for the creation of an information-sharing framework regarding nuclear arms.

In the summit, Yoon referred to attempts to change the status quo by force and said global peace and stability are under threat. He expressed his intention to cooperate with the US in responding to such moves. Observers say Yoon had the situation surrounding Taiwan in mind.