President Yoon Suk Yeol said on Sunday that he does not rule out Japan's future participation in the Washington Declaration, a recent agreement between South Korea and the United States on strengthening the extended deterrence against North Korea's nuclear threats.

The president made the remarks during a question-and-answer session in a joint press conference after summit talks with Kishida at the presidential office in Seoul.

Yoon was answering a question asking if the South Korea-U.S. declaration could be expanded to include Japan.

President Yoon said that the declaration is not complete, and Seoul and Washington need to fill in the content in the process of continued discussion and joint planning and execution.

Yoon hinted that he is open to Japan's participation in the declaration, saying that South Korea can cooperate with Japan whenever Tokyo is ready to join after coordination with the United States.

In a statement in the press conference, Yoon also said that he welcomes the ongoing discussions among the authorities on real-time information sharing of North Korean missile launches, which was agreed upon at the trilateral summit of South Korea, the United States and Japan in Cambodia in November last year.