SEOUL, Dec. 23 (Xinhua) -- The 8th leaders' meeting between China, Japan and South Korea, set to be held in Chengdu this week, was expected to try to find ways for future peace and prosperity in the region as well as closer cooperation among the three nations, a former chief of an international group said.

"During the upcoming meeting, the three leaders are forecast to assess the outcomes (of the trilateral cooperation) for the past 20 years and discuss the direction (of future cooperation) for the next 10 years," Lee Jong-heon, former secretary-general of the Trilateral Cooperation Secretariat (TCS), told Xinhua on Saturday.

This year marks the 20th anniversary of the trilateral cooperation. "For the past 20 years, rapid globalization caused side effects and brought about challenges. Thus, the three countries entered a period of challenges," Lee said.

To overcome the common challenges and secure a persistent peace, stability and prosperity in Northeast Asia, the three countries made a lot of efforts to better understand each other's national policy and the way of thinking via the leaders' meetings, ministerial-level meetings and other cooperation between government agencies for the past 20 years, he noted.

"A lot of advances have been made (in these efforts)," said the former head of the TCS, an international organization that was launched in September 2011 and headquartered in the South Korean capital Seoul with an aim to promote peace and common prosperity among China, Japan and South Korea.

China, Japan and South Korea have signed a trilateral investment agreement and held 16 rounds of free trade agreement (FTA) negotiations so far. The three countries faced an important opportunity of speeding up free trade negotiations as the Regional Comprehensive Economic Partnership (RCEP), a mega trade pact, has made positive progress.

Describing trade protectionism and unilateralism as the biggest challenge faced by the three countries as well as the entire world, Lee said China, Japan and South Korea should fight together to defend free trade and minimize the effect of unilateralism and trade protectionism as they were the biggest beneficiaries of the free trade regime.

"Trade protectionism and unilateralism is not a trend that can last forever even though it will last for the time being," said Lee who noted that if the three countries can maximize respective comparative advantages and create synergy, it would be able to produce a significant economic effect and overcome the challenges.

Referring to the "China-Japan-South Korea+X" as a new trend of future cooperation for the three countries, the former TCS chief said that if China, Japan and South Korea can create a successful model and bear concrete fruits with the concept, it would be of great significance for future trilateral cooperation.

The fundamental meaning of the "China-Japan-South Korea+X" was the trilateral cooperation in the fourth and fifth markets or other sectors by using their respective advantages to avoid overlapping competition while maximizing potentials the three countries have, he noted.

Japan and South Korea give priority to foreign trade and investment, owning notable strengths in information, big data and other high-tech sectors. Meanwhile, China has a huge market and latecomer advantage in 5G and the internet.

Lee said China, Japan and South Korea all had a great potential in the digital economy sector, noting that if the three nations can restructure their industries well under the new paradigm of the Fourth Industrial Revolution, they would be able to open a new bright future.

In terms of differences and disputes facing the region, he said the three countries had difficulties in bilateral relations over historical and territorial issues.

He noted that the difficulties should be overcome as the external challenges, such as unilateralism and protectionism, cannot be surmounted by one country, but by the three countries together.

"The three countries should stop conflict and excessive competition, and strengthen cooperation in a future-oriented way to fight against the challenges faced by all," Lee said.

Lee added that it is the critical time for people, governments and media outlets of China, Japan and South Korea to work together for a "win-win-win" cooperation.