But following months of stalemate on North Korea nuclear talks, Moon's presidency faces a crucial moment, with President Donald Trump and North Korean leader Kim Jong Un set to meet for the second time next week.
Moon, a liberal who took office in May 2017, is desperate for a breakthrough so he can continue engagement with the North that has driven the three-way diplomacy but is now held back by tough U.S.-led sanctions against Pyongyang. There's hope among Moon's supporters that progress by Trump and Kim on the nuclear issue will allow the partial sanctions relief needed for the Koreas to resume joint economic projects that were shelved during previous standoffs.
But Moon may be disappointed in his push for quick sanctions relief.
It remains unclear whether Kim is ready to deal away his nukes, and Washington still sees economic pressure as its best form of leverage over Pyongyang. If the nuclear negotiations break down, Moon could face a serious political dilemma over whether to continue to engage with the North or join another U.S.-led pressure campaign.
A look at the stakes for Moon as Trump and Kim prepare to meet in Vietnam's capital, Hanoi:
Moon, who has preached that Seoul should be in the driver's seat when dealing with Pyongyang, has prioritized improving bilateral relations with North Korea, which he says would help drive nuclear progress between Washington and Pyongyang.
A son of North Korean war refugees, Moon has vowed to build on the legacies of former Presidents Kim Dae-jung and Roh Moo-hyun. Under their "Sunshine Policy," which Moon had a hand in building as Roh's chief of staff, economic inducements from Seoul resulted in temporary rapprochement and summits in 2000 and 2007 with then-North Korean leader Kim Jong Il, Kim Jong Un's late father. In a phone conversation with Trump on Tuesday, Moon said the South was ready to proceed with inter-Korean economic projects to induce further nuclear disarmament steps from Kim.
But Moon is in a tougher spot than his liberal predecessors, who governed when the North's nuclear threat was nascent. Kim's arsenal now includes purported thermonuclear warheads and intercontinental ballistic missiles potentially capable of reaching the U.S. mainland.
The Trump-Kim meeting in Hanoi could be pivotal in determining whether things head toward a stable and nuclear-free Korean Peninsula, or the cementing of the North as a nuclear power. With crucial parliamentary elections coming next year, Moon can't afford a major setback in inter-Korean relations, his strongest issue.
Moon continues to enjoy a good level of public support for his rapprochement with North Korea. But recent polls show there's also growing skepticism among South Koreans, especially among older people, over whether Kim will ever give up his nukes.
"As long as the Kim Jong Un regime is there, North Korea will never abandon its nuclear weapons, even if we pay them hundreds of billions of dollars or trillions of dollars," said Thae Yong Ho, a former North Korean diplomat who defected to the South in 2016.
"The nuclear weapons are gravity that pulls the regime together," Thae said. "They make up for the North getting behind in the inter-Korean competition and provide an instant solution to the North's inferiority in conventional military power against the United States and South Korea."
WORRIES IN SEOUL
While Moon focuses mainly on North Korea, there's criticism that huge problems are being mishandled at home.
There's discontent over a rapidly decaying job market — the 1.22 million South Koreans measured as jobless in January represented the highest number in 19 years. The bad economy has also compromised government efforts toward reforming powerful family-owned conglomerates often accused of monopolistic behavior and corruptive ties with politicians. There's also worry over the long-term effects of a falling birthrate as many women put off marriage and child birth because of financial instability, grueling working hours and limited daycare services.
Deep gender, age and political divides seem to be coming to the head on the eve of an election year, and the ruling liberals have seen their popularity decline over scandals, including the arrest of a pro-Moon provincial governor for his involvement in manipulating online opinions ahead of the 2017 presidential election.
"Inter-Korean relations have been the only thing going well for the Moon government," said Yul Shin, a politics professor at Seoul's Myongji University. "But enthusiasm will quickly wane if we go through event after event without producing real changes on denuclearization."
HOPES OF RESTARTING JOINT PROJECTS
The Koreas in recent months have taken military measures to reduce conventional threats, opened a liaison office in the North Korean border town of Kaesong and vowed to pursue a bid to co-host the 2032 Summer Olympics.
Now they want sanctions dialed back so they can resurrect two major symbols of rapprochement that provided much-needed hard currency to North Korea: a jointly run factory park in Kaesong and South Korean tours to the North's scenic Diamond Mountain resort.
At their third summit in Pyongyang in September, Moon and Kim agreed to make progress on both projects. Kim said later during his annual New Year's speech that the North was ready to restart the projects "without any precondition," while making a nationalistic call for stronger cooperation between the Koreas.
South Korea suspended tours to Diamond Mountain in 2008 after a North Korean soldier shot a South Korean tourist. Seoul's previous conservative government closed the Kaesong park in February 2016 following a North Korean nuclear test.
It's impossible for Seoul to restart the projects under current international sanctions, which have strengthened significantly since 2016 as North Korea sped up its weapons development.
One potential deal could see Pyongyang agree to verifiably dismantle its main nuclear complex at Yongbyon and freeze its nuclear program. Washington, in return, could agree to take steps to free up inter-Korean activities at Kaesong and Diamond Mountain, said Koh Yu-hwan, a North Korea expert at Seoul's Dongguk University and one of Moon's policy advisers.
The Security Council would probably need to pass an entirely new resolution on the North for inter-Korean economic activities to resume, which is difficult to imagine until Kim takes deeper steps toward verifiably and irreversibly relinquishing his nuclear arsenal, said Lim Soo-ho, an analyst from the Seoul-based Institute for National Security. Even if this happens, it still leaves U.S. unilateral sanctions, which would put South Korean companies doing business in the North under the threat of U.S. boycotts.
Trump would need to go through an exhaustive process to soften U.S. sanctions, Lim said, because of a 2016 law that demands significant progress not only on North Korea's nuclear disarmament but also on its dismal human rights record for punitive measures to be suspended or removed.