Japan, the United States and South Korea are planning to hold a three-way summit on the fringes of a NATO leaders' gathering in Spain next week, diplomatic sources close to the matter said Tuesday.

Leaders from the three nations will likely discuss imminent issues such as responses to North Korea, which has been repeatedly launching ballistic missiles despite mounting criticism from the international community, the sources said.

It will be the first top-level meeting between the three countries since September 2017. If realized, Japanese Prime Minister Fumio Kishida, U.S. President Joe Biden, and South Korean President Yoon Suk Yeol will hold talks together for the first time.

At the meeting, the three leaders are expected to affirm their cooperation to realize a free and open Indo-Pacific in the face of China's growing presence in the East and South China seas, according to the sources.

In addition to the trilateral talks, the Japanese government is also considering a four-way summit with South Korea, Australia and New Zealand on the sidelines of the NATO meeting.