Hong Kong (CNN) The date for their meeting is still not set, but when President Donald Trump finally meets North Korea's Kim Jong Un, the specter of China will also be in the room, a potent signal to the American President that the young reclusive leader has support for his cause from the region's most formidable presence.

Along with shoring up a rocky alliance, the two-day visit by Kim to Beijing was also designed to show Washington and Seoul that Kim wasn't without his own diplomatic arsenal as he attempts to push for sanctions relief and recognition of North Korea as a legitimate nuclear power.

South Korea admitted on Wednesday that it hadn't been involved in Kim's trip to Beijing. Senior presidential press secretary Yoon Young-chan told reporters: "What is happening now is beyond what the (government) has been predicting and (Seoul) will need to keep an eye on the situation with all possibilities in mind."

"The very fact of this meeting alone, and certainly the tenor of the Chinese statement about it, really does increase Kim Jong Un's leverage in the upcoming talks. It shows that Kim has a friend in Beijing," said Adam Mount, a senior fellow and director of the Defense Posture Project at the Federation of American Scientists, where he covers US nuclear strategy, deterrence and North Korea.

"It means the Trump team is going to be navigating really narrow straits here. It's hard to overstate how dramatic this development is," Mount said.

China 'will continue to play a constructive role'

"We speak highly of this visit," Chinese President Xi Jinping told Kim, according to Xinhua, China's state-run news agency, which reported on the visit after Kim departed Beijing. Xi added that China "appreciates the important efforts made by the DPRK (Democratic Republic of Korea)" regarding "positive changes" that have occurred on the Korean Peninsula this year, Xinhua reported.

The messages out of both Beijing and Pyongyang following the visit are meant to emphasize to all parties that there can be no deal with North Korea without China's involvement.

Xi noted that "China will continue to play a constructive role on the issue (of talks) and work with all parties, including the DPRK, toward the thaw of the situation on the Peninsula," Xinhua reported.

The "situation on the Peninsula" refers to not only the tension over North Korea's nuclear program, but the presence of US troops to the south and the outlying waters where US and South Korean militaries regularly conduct naval exercises

North Korean leader Kim Jong Un, his wife Ri Sol Ju, Xi Jinping and his wife Peng Liyuan pose for a photo at Diaoyutai State Guesthouse in Beijing.

"To the US, denuclearization is denuclearization of North Korea. To Kim Jong Un, denuclearization applies to the whole peninsula, which includes the South," said David Maxwell, retired US Army Special Forces colonel and a fellow at the Institute of Korean American Studies.

"When the regime talks denuclearization, they require the South Korea-US alliance to be ended, US troops removed from the peninsula and an end to extended deterrence and the nuclear umbrella. Once that condition is met, then the North will begin the process of denuclearization," he said.

Trump himself tweeted Wednesday that he'd heard from Xi about Kim's visit, saying: "For years and through many administrations, everyone said that peace and the denuclearization of the Korean peninsula was not even a small possibility. Now there is a good chance that Kim Jong Un will do what is right for his people and for humanity. Look forward to our meeting!"

'Our greatest asset'

The China visit has added a layer of complication for Trump that had long been dormant because of years of estrangement between Pyongyang and Beijing.

Now that ties are seemingly mended, that bodes ill for the White House, said Mount.

"The division between Beijing and Pyongyang was really our greatest asset with respect to North Korea," he told CNN. "If that narrows even slightly, that's a sea change. It changes the outlook for negotiations that we have to adjust for very rapidly. It's clear both Pyongyang and Beijing won't be dictated to by Seoul and Washington, but also develop their own agenda. We should be aware that it might be a coordinated agenda," Mount said.

The notion that might have held sway until this week, that North Korea was prepared to meet with Trump and put "nukes" on the table, is no longer the case, said Mike Chinoy, a former CNN correspondent and author of "Meltdown: The Inside Story of the North Korean Nuclear Crisis," who has made regular visits to North Korea in the past.

"This didn't look to me like a browbeating summit, that is not the dynamic at all," Chinoy remarked. Rather, it appears that Kim has been shoring up his alliances in anticipation of the meeting with Trump.

North Korean leader Kim Jong Un smiles as he and Chinese counterpart Xi Jinping attend a banquet at the Great Hall of the People in Beijing.

Daniel Russel, who helped formulate President Barack Obama's Asia Pacific policy, agrees.

"We might be seeing success in the North Korean effort to divide the five countries that have been involved in the effort. It's a standard gambit for North Korea to try to undermine the unity of the international community," he told CNN, referring to the US, South Korea, Japan, China and Russia, which have historically been engaged in talks involving North Korea.

He said it was "critically important" for the US to communicate and cooperate with China.

"China might want a more modest settlement than the US wants, or can live with," Russel said. "It's on us, the US I think, to continue to find common cause, not only with China, but also with South Korea and Japan, and although difficult, with Russia."

The John Bolton approach

Trump's newest national security adviser, John Bolton, a past US ambassador to the United Nations and noted hawk, has discounted North Korea's sincerity , believing that the Kim regime's appeal for talks masks a ploy to bide time until its nuclear program is up and running.

Incoming Secretary of State Mike Pompeo has in the past advocated for regime change in North Korea

"There'll be very sharp battles in Washington between people who want to test North Korea and those who have been itching to pick a fight with North Korea, and may finally hope that this is their chance," said Chinoy.

Some of that will depend on how large a role Beijing will play, and how much Chinese influence Washington is prepared to stomach.

"We should not agree to allow China to host the summit or even be present at the summit," said David Maxwell. "That said, the best outcome for this summit is simply a meet and greet between Trump and Kim Jong Un, an exchange of positions and an agreement to allow the diplomatic experts to begin the process of negotiating an agreement," he told CNN. "We should not expect any breakthroughs."

Kim Jong Un, left, and Xi Jinping, right, are seen at a banquet in this photo released by North Korean state media.

And while the White House recalibrates its approach to the summit following the Xi-Kim meeting, it may have to brace itself for the entrance of another world power keen on not being left out of future gatherings: Russia.

On Wednesday, Russia signaled its approval of the Xi-Kim dialogue in Beijing. The Foreign Ministry added that Russia aimed to continue close cooperation with China to resolve tensions on the peninsula by "purely diplomatic means."