Defense chiefs from South Korea, Japan and the United States have agreed to start as planned a real-time data sharing plan on North Korean missiles in December, South Korea's Defense Ministry said Sunday.

U.S. Defense Secretary Lloyd Austin met his South Korean counterpart Shin Won-sik in Seoul on Sunday with Japanese Defense Minister Minoru Kihara joining the meeting online.

The ministers discussed strengthening their three-way cooperation in the face of "severe security environments," Kihara told reporters. It was the first time for the three ministers to hold such a gathering, he said.

"We confirmed that we are steadily making adjustments, bringing the process to the final stage," Kihara added.

U.S. President Joe Biden agreed with South Korean President Yoon Suk-yeol and Japanese Prime Minister Fumio Kishida at an Aug. 18 summit that by the end of this year the three countries would share North Korea missile warning data in real time.

The ministers also condemned growing military cooperation between North Korea and Russia as a violation of U.N. resolutions, the South Korean Defense Ministry said in a statement, and also stressed the importance of peace and stability across the Taiwan Strait.

Separately, Gen. Charles Q. Brown, chairman of the U.S. Joint Chiefs of Staff, held talks with his South Korean counterpart in Seoul on Sunday, the South Korean military said.

In his first visit to South Korea since he took office in October, the top U.S. general discussed the "continuous provocations" of North Korea including missile launches, and reaffirmed the United States' commitment to the defense of South Korea, the South Korean joint chiefs of staff said in a statement.