(CNN) South Korean officials met with Chinese President Xi Jinping on Monday, as part of an effort to bring jittery regional powers on board with US President Donald Trump's decision to accept a face-to-face meeting with North Korean leader Kim Jong Un.

Seoul's lead envoy, National Security Advisor Chung Eui-Yong, sat down with Xi in Beijing for 35 minutes on Monday, as a parallel delegation headed to Tokyo to brief Japanese Prime Minister Shinzo Abe on the attempts to open talks with Pyongyang on its nuclear and missile program.

"I support the US-NK talks. I am delighted that S. Korea's efforts have made great progress in the overall Korean Peninsula situation and that close dialogue between NK and the US has been achieved," Xi said, according to a statement from the South Korean presidential office.

Chung met China's top diplomat, state councilor Yang Jiechi, for three hours before meeting Xi, the South Koreans said.

China, which appears to have been left on the sidelines as South Korea has orchestrated the rapprochement with the North, attempted to take partial credit for the developments over the weekend.

An op-ed in government mouthpiece People's Daily said that the diplomatic breakthrough followed China's "dual-suspension" proposal, in which North Korea would freeze its missile-testing program in return for the suspension of US-South Korean military drills.

But despite China's claim, North Korea has yet to offer any concrete steps to whittle back its nuclear program, while Kim told a South Korean delegation to Pyongyang last week that he understands the need for Seoul and Washington to continue the joint drills.

In a call with Trump on Friday, Xi appeared to welcome the prospect of talks.

"The two leaders welcomed the prospect of dialog between the United States and North Korea, and committed to maintain pressure and sanctions until North Korea takes tangible steps toward complete, verifiable, and irreversible denuclearization," an official White House statement said.

South Korean Foreign Minister Kang Kyung-wha will also be traveling, as she visits Washington this week to meet with US Secretary of State Rex Tillerson, who has been on a five-nation tour of Africa during which the apparent breakthrough was announced.

South Korean President Moon Jae-in, who has led the overtures to the North, said Monday that "important changes" were happening in East Asian geopolitics.

"Should we succeed, there will be dramatic changes in world history, and (South) Korea will have played the leading role," he said at a meeting of his senior advisers at the presidential Blue House.

Silence from North Korea

Amid the flurry of diplomatic activity, there has been no word from Pyongyang about the talks that the regime is said to have proposed.

North Korea's state media has not reported on the developments and the regime has yet to respond officially to Trump's acceptance of the invitation to talks.

US Secretary of State Rex Tillerson confirmed on Monday that there had been no direct communication with North Korea yet since Trump accepted Kim's offer of a meeting last week.

"It's very early stages. We've not heard anything directly back from North Korea, although we expect to hear something directly from them," Tillerson said, before adding that there were several necessary steps the administration needed to go through to decide on a location and the scope of discussions.

He urged the public to "remain patient, and we'll see what happens."

Earlier on Monday, the South Korean Unification Ministry said no further steps had been taken with Pyongyang to arrange the meeting.

"I think North Korea needs time to organize their position and is being careful and cautious in approaching regarding the summit," said Unification Ministry spokesman Baik Tae-hyn.

"In the meantime, the Unification Ministry will play an appropriate (and) central role in carrying out this process."

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Mike Chinoy, CNN's former senior Asia correspondent and author of "Meltdown: The Inside Story of the North Korean Nuclear Crisis," said "an asterisk" would hover above the talks until North Korea officially confirms its buy-in.

He said that, in delivering the invitation to Trump orally, it was possible that the South Korean envoys may not necessarily have accurately conveyed to the US leader what Kim said, "let alone what he meant," without a written record of the invitation.

"It's all well and good that they're making friendly noises to one another, (but) to take what a South Korean official says at face value without any formal confirmation from Pyongyang is very odd," he told CNN.

"Don't count your summits until they hatch."

Tough sell

The South Korean delegations may have a tough job to sell the developments to Beijing and Tokyo, which are both wary about the talks -- although for different reasons.

The Chinese side would be "happy but conflicted" about the developments, according to Stanley Roth, a former US assistant secretary of state for East Asian and Pacific affairs.

"Of course, anything that defuses the situation, makes military action less likely, is very positive for them. If it can lead to a negotiating process, even better," he told CNN's Fareed Zakaria.

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Roth added that "there's probably a bit of resentment that North Korea (could meet) with the US President before meeting with the Chinese President," a development that he described as "absolutely extraordinary."

Japanese Prime Minister Shinzo Abe has repeatedly stressed the need to maintain pressure on North Korea to commit to ridding the peninsula of nuclear weapons.

Abe, briefing reporters after speaking to Trump and Secretary of State Rex Tillerson last week, said that the US and Japan had agreed to "keep putting maximum pressure until North Korea takes concrete actions toward denuclearization."

Chinese 'angst'

Chinoy said China had been "bystanders" in the recent thaw in relations between North and South Korea.

"Given their enormous stakes in the region and Xi's notion of dominance in the region, there (will be) concern that this is happening without Chinese input," he said.

"My guess is that the public line will be: 'We support dialog,' but there will be a bit of angst that they're not shaping events."

Zhang Liangu, a former professor of international strategy at the Chinese Communist Party's Central Party School and an expert on North Korea, says that thought is divided on how much China should actively involve itself in the talks.

"The first school of thought believes that North Korea is our doorstep (and) unless it disarms, there will always be risks of a war next to China.

"The second school thinks China shouldn't insert itself in the talks as it's not directly involved in this issue. Currently it seems that the rhetoric of the Chinese Ministry of Foreign Affairs aligns with the latter, saying the issue should be handled directly by North Korea and the US."

At a regularly scheduled press briefing Monday, Chinese Ministry of Foreign Affairs spokesman Lu Kang insisted that Beijing was involved in the process.

"China is in close contact with all parties related in an effort to ease the tensions on the peninsula and bring the issue back to the track of political settlement through negotiations and consultations as soon as possible."