Trump and Moon, who will meet for the first time Thursday, face the same challenge: a belligerent Pyongyang that has refused, for the most part, to comply with international calls for denuclearization.
The two leaders have also been the targets of North Korea bluster. Pyongyang recently claimed Trump's immigration policy is a U.S. version of Nazism, and accused Moon of following an "imperialist" ally.
But despite Moon's statements stressing commonalities with Trump's approach to North Korea, others are not so sure whether the two men, an American billionaire real estate developer, and a South Korean human rights lawyer, would see eye to eye at the crucial summit.
Marcus Noland, an expert on North Korea at the Peterson Institute for International Economics in Washington, D.C., told UPI in a phone interview the United States and South Korea are on a "potentially dangerous trajectory at this point" because of different approaches to North Korea.
"The problem we face now is just at the moment where there is some evidence both the United States and China are starting to increase pressure on North Korea, the Moon government comes along and is signaling with various degrees of enthusiasm from day to day a more forward-leaning engagement policy," Noland said, adding pressure with a side of diplomacy is an approach the United States and South Korea should share.
China is a key player, but a South Korean lifeline to Pyongyang could upset the balance of cooperation on sanctions, the analyst added.
"It's important to remember Beijing will not take a harder line on North Korea than Seoul does," Noland said. "So if Seoul goes in there and starts this kind of engagement, whatever kind of cooperation we've been getting out of China over the last six months is going to dry up."
Chief among Noland's concerns is Moon's rhetoric regarding the Kaesong Industrial Complex, a jointly operated factory park in North Korea that shut down in 2016.
Moon had called for a reopening in the course of his presidential campaign, but according to Noland, any South Korea move to reopen the complex would "bring it into conflict with the United States," as well as violate United Nations Security Council sanctions Resolution 2321.
While sanctions may come up in talks between Trump and Moon, others hope the summit could be an opportunity for both leaders.
Jenny Town, the assistant director of the U.S.-Korea Institute at Johns Hopkins University, says Trump's lack of familiarity with South Korea could be corrected with the meeting on Thursday.
"The summit is an important opportunity for President Moon and President Trump to get to know each other," Town told UPI. "South Korea has not necessarily been as high on Trump's radar as China and Japan. I think it's a chance for Moon Jae-in to go in and explain regional security issues from South Korea's perspective, because that's been really missing from Trump's understanding of Asia."
South Korean concerns about Trump began well before his election, when he criticized the U.S. ally, as well as Japan, for their dependence on American forces for defense against North Korea's military threats.
Trump had said both countries "don't pay us," although burden sharing has prevailed in Seoul and Tokyo.
The president later reaffirmed the U.S.-South Korea alliance with then-President Park Geun-hye, but a vacuum of political leadership following her impeachment has raised more questions.
Trump has also invited uncertainty with a departure from the script of "strategic patience" of the Obama administration. Waiting out North Korea's lack of willingness to denuclearize, while escalating sanctions, has not worked, Trump administration officials have said.
Neither Noland nor Town, however, said they see a radical departure in U.S. policy regarding North Korea at the Trump White House.
"To be perfectly honest, I can't really tell a whole lot of difference between Trump's policy and the previous policy of strategic patience," Noland said, describing the new "maximum pressure and engagement" policy of the current administration as strategic patience "on steroids."
"The reason is very simple. The United States does not have any good options when it comes to North Korea."
It may also be too early to tell whether the new approach is working, Town said.
"The real measure of whether or not [Trump's] policy is different from strategic patience is going to be whether or not they can get to the engagement phase, and are the conditions for engagement realistic enough to start dialogue," Town said, adding strategic patience did not work because lack of engagement on both sides "simply strengthened North Korea's resolve to move forward with nuclear weapons."
"It gave them a lot of time to do it," Town said.
The summit also comes at a time when the death of 22-year-old Otto Warmbier has sent shockwaves in the United States and in South Korea, where more than 30,000 North Korean defectors have resettled after fleeing the Kim regime.
The Ohio native died in his hometown after more than a year in North Korea custody, and Trump described the circumstances of his death a "disgrace."
Greg Scarlatoiu of the Committee for Human Rights in North Korea in Washington, D.C., said the Warmbier case should come up during the summit because it addresses the concerns of both leaders.
"It's a true tragedy. It's not only an American issue," Scarlatoiu said. "North Korea has a long history of brutalizing its own people."
Pyongyang still holds three Americans in detention, and six South Koreans continue to be held in the country.