A former diplomat who advises the South Korean ruling party's presidential nominee Lee Jae Myung has expressed eagerness to strengthen security cooperation with Japan and the United States through the use of Seoul's military-intelligence sharing agreement with Tokyo.

Wi Sung Lac's remarks, made during an interview in Seoul this week, are a departure from the policy of current President Moon Jae In's administration, which has made it clear that South Korea could scrap the bilateral agreement anytime depending on how already testy South Korea-Japan ties fare.

Wi, who serves as the chairman of a foreign affairs committee set up in the Lee campaign within the Democratic Party, said the General Security of Military Information Agreement, or GSOMIA, represents a meaningful stepping stone for security cooperation between the two countries.

Wi Sung Lac speaks in an interview with Kyodo News in Seoul on Dec. 15, 2021. (Kyodo)

"We should definitely make good use of the pact so that the framework for security cooperation could be solidified," the former ambassador to Russia said, advocating greater operational use of the agreement.

The 2016 agreement enables the two U.S. allies to exchange sensitive information about North Korea. It was set to expire in November 2019 after South Korea launched a termination process, but the country ultimately decided against it.

In announcing the planned termination in August that year, the Moon administration had cited Tokyo's move to tighten export controls on some materials crucial to the South Korean technology industry.

While Lee has often made remarks widely interpreted as hard-line toward Japan, Wi denied the candidate has ideas that are anti-Japanese. Lee "understands the need to improve relations and that, if he were elected, (improving the relations) would be a pressing matter for the moment," he said.

Wi also addressed a territorial dispute over South Korean-controlled islets known in Japan as Takeshima and as Dokdo in South Korea. The dispute flared up again recently when a top South Korean police official visited them to Tokyo's dismay.

Wi stuck to Seoul's position that the Sea of Japan islets are part of South Korea. But he called for action conducive to improving relations. "There is no need to damage the atmosphere by doing something which would not help improve them."

Wi, who also served as South Korea's top envoy on issues related to North Korea's nuclear programs, stressed the usefulness of three-way security cooperation between the United States, South Korea and Japan when dealing with issues such as potential threats from North Korea.

But for that arrangement to work, Wi said, "What is most important is a strong agreement on the need to improve (South Korea-Japan) ties."

Wi also stressed the need for a formal declaration on ending the 1950-1953 Korean War, as a way to make the North's denuclearization move forward -- a policy stance not shared by the main opposition People Power Party nominee, former Prosecutor General Yoon Suk Yeol, whom Lee is expected to face in the March presidential election.