National Security Adviser Shin Won-sik (center) (Yonhap)

The leaders of South Korea, the United States and Japan are expected to hold a trilateral summit near the end of this year, according to South Korea's national security adviser Saturday.

Earlier in the day, Seoul's presidential office said US President Joe Biden has proposed holding a trilateral summit by the end of this year.

He made the proposal in a message conveyed to South Korean President Yoon Suk Yeol through Secretary of State Antony Blinken at the Association of Southeast Asian Nations summit in Laos.

The trilateral summit, if realized, will be a follow-up to the historic trilateral meeting held at Camp David last year and will bring together Yoon, Biden and Japan's new Prime Minister Shigeru Ishiba.

"If the trilateral summit takes place, it will likely be around the end of the year, following the APEC and G20 meetings," National Security Adviser Shin Won-sik said in an interview with TV Chosun. "A consensus has been reached to hold the summit before the year ends."

The Asia-Pacific Economic Cooperation summit and the Group of 20 summit are both scheduled for mid-November.

When asked about North Korea's recent claims that South Korea had sent unmanned drones, Shin said, "It would not be wise to respond to every single claim made by North Korea."

North Korea claimed Friday that South Korea sent unmanned drones carrying anti-North propaganda leaflets over Pyongyang on Oct. 3, as well as on Wednesday and Thursday of this week. South Korean Defense Minister Kim Yong-hyun, however, said he could not confirm the North's claim.

Shin also mentioned that it appears North Korea may not have included leader Kim Jong-un's "two hostile states" doctrine in its revised constitution.

Earlier this week, North Korea amended its socialist constitution during a key parliamentary session, but it has not disclosed whether it removed unification-related clauses or clarified the nation's territorial boundaries, including its maritime border, in line with Kim's directives.