(CNN) President Donald Trump will sit down with his South Korean counterpart Moon Jae-in at the White House on Thursday to discuss how to revive the diplomatic process between the US and North Korea.

However, aides to both leaders have told CNN they are nervous the meeting could do more harm than good due to diverging views on how to bring Pyongyang back to the table.

During his first face-to-face meeting with Trump since February's failed summit with North Korean leader Kim Jong Un in Hanoi, Vietnam, Moon will attempt to convince the US President that there are "signs of progress" and that North Korea is willing to return to negotiations, according to two sources familiar with the matter.

The already high-stakes meeting took on added significance after Kim issued a stark warning seemingly aimed at the US, saying North Korea needed to "deal a telling blow to the hostile forces who go with bloodshot eyes miscalculating that sanctions can bring the (Democratic People's Republic of Korea) to its knees," according to North Korean state media reports.

Kim's comments were made to the Fourth Plenary Meeting of the Seventh Central Committee of the Worker's Party in Pyongyang on Wednesday but were reported by North Korea's state news agency (KCNA) on Thursday.

They come on the heels of warnings from Pyongyang that Kim could change course after Trump walked out of the Hanoi negotiations, leaving the North Korean leader and his team bewildered, according to two sources familiar with the matter.

In his role as intermediary, Moon will raise 'specific points' with Trump on Thursday in an attempt to break the stalemate, the sources added, much like he did ahead of the first inter-Korean summit in June of 2018.

"Moon's objective is to reactivate talks," one source said. "The best thing (Moon) will be aiming for is to have the talks resumed and possibly another summit."

While Trump has indicated that he wants a third summit with Kim, both sides have dug in after the Hanoi meeting failed to yield any sort of an agreement. Moon hopes he can encourage Trump to agree to some sort of compromise that might help grease the wheels for further engagement between the US and North Korea but could face a challenge from some within the administration.

Trump betting on Moon but Kim doesn't seem to be listening

After Trump opted to walk away from the table in Hanoi without a deal, his first call was to Moon.

Trump, with an upbeat demeanor, asked Moon to tell Kim that things would move forward and to encourage him to come back to the table, according to multiple sources familiar with the phone call.

Despite Trump's request, Moon has not had a call with Kim, according to a South Korean government adviser. Another senior South Korean government official, who said that there are still lines of communication between the two countries that sometimes go through China or Russia, wouldn't confirm that Moon has gotten hold of the North Korean leader either.

And that is not the only instance in which North Korea has rejected South Korea's recent overtures. Last month, the North Koreans at the inter-Korean liaison office left without warning. And the inter-Korean projects between the two countries, such as remains recovery and freedom of navigation projects, were halted.

"Ever since the second US-DPRK summit in Hanoi the ROK-DPRK military relationship is not as great as we had hoped. And as such the ROK is engaging its own individual efforts in the area, including demining as well as remains recovery, on its own," said a senior South Korean government official.

Moon will push for a 'good enough' deal

On Thursday, Moon is facing perhaps his greatest diplomatic challenge to date: kickstarting denuclearization talks between the US and North Korea amid rising tensions and uncertainty.

Moon Chung-in, a Yonsei University professor and an adviser to Moon, says that South Korea wants to lay down some kind of "time-bound roadmap" with incremental implementation. And, perhaps most importantly, the south is hoping for an "early harvest" or a "good enough deal" -- which are being cast by South Korean officials as what is needed to keep alive the momentum and convince the North Koreans to stay at the table.

"A small deal is not a bad deal," explained a senior South Korean government official. "It depends on how small it is. It is a good deal if it is good enough to help us make an early harvest that allows us to see the nuclear past and present of North Korea."

The official indicated that a small deal could include returning to the idea of dismantling Yongbyon, North Korea's nuclear research facility, or smaller-scale progress like opening a US-NK liaison office or agreeing to a declaration of the end of the Korean war.

It is unlikely, however, that the Trump administration would bite at a suggestion they settle for a smaller, less ambitious agreement with Kim. Trump demonstrated in Hanoi that he wants a big deal that gets to the heart of North Korea's nuclear program and goes beyond the North Koreans dismantling Yongbyon.

Sanctions a key sticking point

Another approach that Moon could take would be to advocate for a lifting of US sanctions on North Korea. That is what Kim aggressively pushed for during the Hanoi summit.

Exactly how Moon plans to approach sanctions relief with Trump remains unclear. But many observers expect he will try to lure Trump in that direction and warn that it could create a quagmire.

Moon is in a tough spot. One source said that he is under pressure from the North Korean side to do more to convince Trump to reach a compromise on partial sanctions relief in return for incremental steps and keeping talks going.

But a senior South Korean government official, when asked if Moon will press Trump for sanctions relief, said that he is "not going to do that." The official explained that sanctions need to be looked at closely but lifting them" depends on how aggressively North Korea denuclearizes once an agreement is struck.

There are projects like tourism between the north and the south or reopening the Kaesong Industrial Complex that would require sanctions waivers from the UN.

The Trump administration is unlikely to advocate for those waivers, given that administration officials have said that sanctions can't be lifted until there is complete denuclearization.

Secretary of State Mike Pompeo told members of Congress Wednesday "we need to continue to keep the pressure on" when it comes to sanctions on North Korea. He promised that "the North Korean economy will shrink this year."

Trump has, however, demonstrated an eagerness to keep the momentum alive with Kim since Hanoi. He even tweeted that new sanctions are not needed after the US Treasury announced new designations on two Chinese entities.

Both countries want another meeting with Kim

Both US and South Korean officials say that their leaders want another summit with Kim.

South Koreans expect that Moon will meet with Kim after meeting with Trump, but it is unclear whether he'll be able to announce anything Kim wants to hear given the potential for clashes on Thursday.

South Koreans are also wary of the impact that national security adviser John Bolton may have if he is heavily involved in the meeting with Moon or in any future US-NK summits, given the adverse impact they believe he had on the summit in Hanoi.

"There is widespread understanding that Mr. John Bolton (must) have played a very, very negative role," Moon Chung-in said of the summit in Hanoi, speaking in his personal capacity to a group of reporters who traveled to Seoul as part of a journalism fellowship program sponsored by the Atlantic Council Foundation and the Korea Foundation.

Kim's next move?

And Kim's next move will of course be crucial. Just hours before Trump and Moon meet in Washington, Kim is scheduled to speak at the Supreme People's Assembly which is the first meeting of North Korea's parliament. And early next week North Korea will celebrate the birthday of Kim's grandfather, Kim Il Sung, the founder of North Korea.

Kim is still weighing options that include taking provocative measures, such as a satellite launch, in an attempt to regain leverage by raising tensions with the US or go the other way: attempt to resume diplomacy while continuing to seek sanctions relief, a source said.

Plans are also in the works for Kim to visit Russian President Vladimir Putin. South Koreans say they are not worried, but that visit could further complicate the diplomacy between the US, North Korea and South Korea.