In the highly formalized world of China-North Korea relations, Xi Jinping's trip to Pyongyang carries enormous symbolic significance. Although less certain, it may also yield outcomes that could influence both countries' relations with the U.S.

With tensions over trade, Taiwan and Hong Kong dominating Xi's diplomatic agenda, the trip also offers some welcome breathing space as the traditional allies work to strengthen ties that have been rocky at times, usually in relation to North Korea's nuclear weapons program.

Though relations between Xi and the North's leader Kim Jong Un got off to a bumpy start, Kim has now made four visits to China since March 2018, each time taking care to show the proper deference to his country's most important ally and provider of aid, trade and diplomatic support. The timing of Xi's first visit as president ahead of the G-20 summit in Japan later this week seems to signal an intention that China remains a key player in peninsular affairs.

"The stability of the Korean Peninsula and realizing denuclearization are of vital importance to China," said Lu Chao, an expert on bilateral relations at the Liaoning Academy of Social Sciences in northeastern China. "China intends to play an important role as a mediator."

Such state visits are imbued with vast historical significance by the two countries, who still emphasize the role of revolutionaries such as Mao Zedong and Kim's grandfather, Kim Il Sung, in forging a relationship once referred to as being "as close as lips and teeth."

That changed after China embarked on economic reforms four decades ago while the North stuck to orthodox communism's shibboleths of state ownership and central planning, even as its economy tanked and starvation grew.

Necessity drove North Korea back into China's embrace, but the regime's testing of nuclear weapons and the missiles to deliver them destabilized the region and angered Beijing's stability obsessed leaders.

At their meeting, Xi will likely reiterate China's hopes for a restarting of six-nation denuclearization talks it formerly hosted. China had accrued considerable political cachet for doing so at a time when the North looked amenable to ending its weapons programs in return for economic assistance and the prospect of a formal peace agreement ending the 1950-53 Korean War before later abandoning the negotiations.

Beijing is also anxious to encourage North Korea's self-declared shift away from nuclear confrontation toward economic development.

Any movement on the nuclear issue could also lend new momentum to currently stalled U.S.-North Korea talks, Lu said, offering Beijing potential rewards from Washington amid the spiraling trade feud between them.

Yet, despite China's ongoing support for harsh U.N. economic sanctions, Xi is unlikely to push so hard as to put China's influence with Pyongyang at risk. China is a major power that is very significant for the stability of the Korean Peninsula and takes its role as mediator seriously, Lu said, emphasizing that Beijing is looking to Pyongyang to make an effective guarantee on the nuclear issue and take concrete measures.

"To China, the best way to guarantee its long-term influence would be to solidify its special relationship" with North Korea, Tong Zhao of the Carnegie-Tsinghua Center for Global Policy wrote in an emailed statement.

"By demonstrating its unique relations with DPRK at a time when neither Washington nor Seoul is able to resume high-level engagements with Pyongyang, Beijing is signaling to Washington that it is still a helpful, constructive and indispensable partner to resolve important regional problems," Tong wrote.

Pang Zhongying, a professor at Renmin University's School of International Studies in Beijing, said Xi and Kim's discussions will likely have a bearing on the content of meetings at the G-20 summit.

"By having a first-hand view on his visit to North Korea, Xi will be able to brief the U.S. leader and other leaders if needed," Pang said. "China no doubt hopes to show its influence in this respect at G-20 and North Korea will be paying attention."

Pang is less certain about how the U.S.-China trade war might factor into the Xi-Kim talks. President Donald Trump has previously said that that China's help on dealing with North Korea could help it win better trading terms, although that was before trade talks broke down and the U.S. hardened its position.

In contrast to knotty issues such as Hong Kong — where opponents of Beijing's increasing grip over the semi-autonomous Chinese territory have held massive street protests this month — and Taiwan, whose independence-leaning government has defied China's claim to the island republic, North Korea offers a relatively simple formula for engagement.

"As China-U.S. strategic rivalry grows, China would be more preoccupied with maintaining its geopolitical influence over the Korean Peninsula vis-à-vis the U.S.," Tong said.