SEOUL - When South Korean President Moon Jae-in successfully mediated the historic first summit between the leaders of the United States and North Korea in 2018, hopes rose for peace on the Korean Peninsula.

Three years on, nuclear talks with Pyongyang are stalled and the North is still testing missiles.

Still, these would count as Mr Moon's biggest achievements so far on the North Korean front:

- Holding three summits with North Korean leader Kim Jong Un in 2018, two at the border village of Panmunjom and one in Pyongyang.

- Signing the Panmunjom Declaration in April 2018, in which the North and South agreed to improve ties, engage in more dialogue and cooperation as well as establish a joint liaison office.

- Becoming the first-ever South Korean leader to address a North Korean audience of 150,000 in a packed stadium in Pyongyang in September 2018. He called for a complete end to 70 years of hostility, permanent removal of nuclear weapons, and reunification.

- Witnessing the signing of an inter-Korea military pact to ease military tension and halt all hostilities in September 2018. Experts described it as a de-facto declaration to end the 1950-53 Korean War, which was merely halted with an armistice.

- Hosting the 2018 Pyeongchang Winter Olympics which served as a platform for sports diplomacy with North Korea and became a springboard for more talks.

Professor Lee Jae-min of Seoul National University said the complexity of the North Korean issue means "there is still a long way to go for final resolution".

But Mr Moon has already made "meaningful progress" in his four years in office, paving the way for his successors, added Prof Lee.

"Moon's legacy will be that he established an important way station to the final destination," he said.