SEOUL (Reuters) - The national security advisers of the United States, South Korea and Japan met over the weekend to discuss North Korea and the “complete denuclearization of the Korean Peninsula,” South Korea’s presidential Blue House said on Monday.

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The two days of meetings could also help prepare the way for a meeting between U.S. President Donald Trump and North Korean leader Kim Jong Un.

They were the latest in a flurry of diplomatic activity spanning Asia, the United States and Europe before North Korea’s planned summits with the South and the United States.

South Korea’s National Security Office chief, Chung Eui-yong, met U.S. national security adviser H.R. McMaster and Japan’s national security adviser, Shotaro Yachi, to discuss summit meetings between Kim and South Korean President Moon Jae-in, the Blue House in Seoul said.

They also discussed the possible meeting between Trump and Kim, it said.

The security advisers from the three countries talked about the “complete denuclearization of the Korean Peninsula,” and agreed that “it was important to not repeat the mistakes of the past” and to work together closely, the Blue House said.

In a statement, the White House also referred to avoiding mistakes of the past and said the advisers met to discuss the summit and the “permanent” denuclearization of the Korean Peninsula.

A senior North Korean diplomat left for Finland on Sunday for talks with former U.S. and South Korean officials, South Korea’s Yonhap News Agency reported.

That followed three days of talks between North Korea’s and Sweden’s foreign ministers on security on the Korean Peninsula.

Sweden “engaged heavily” on the issue of U.S. detainees during the talks between the two foreign ministers, CNN reported on Sunday, citing unidentified sources with knowledge of the negotiations.

North Korea is pursuing nuclear and missile programs in defiance of U.N. Security Council sanctions and has made no secret of its plans to develop a missile capable of reaching the U.S. mainland.