For some China watchers his absence is a bad omen for the state of Sino-US relations despite Trump's continued insistence that Xi is a close friend.
As the flames of a trade war between China and the United States lick higher, one top Chinese leader expected to help handle relations with Washington has been conspicuous for not taking a public role in the dispute - Vice President Wang Qishan.
Known in Chinese government circles as "the firefighter" for his central role in tackling issues like corruption and domestic financial problems, Wang also has experience dealing with the United States - leading annual economic talks with Washington when he was a vice premier.
As a result, Wang had been tipped by foreign diplomats to take a central position in handling US President Donald Trump's administration when he became vice president.
These expectations had been heightened when prior to his appointment in March, Wang had private meetings with US ambassador to China Terry Branstad, and with former Trump adviser Steve Bannon. He also held closed-door meetings with US executives in recent months, sources in the US business community say.
But aside from the occasional public meeting with US visitors - the last time was in mid-May when he met US business executives in Beijing - and the odd appearance elsewhere, including at a forum in Russia in late May, Wang has kept a low profile.
The week before last, for example, the only news he appeared to make was when he met Bangladesh's foreign minister and when he was appointed honorary president of the Chinese Red Cross.
For some China watchers his absence is a bad omen for the state of Sino-US relations despite Trump's continued insistence that Xi is a close friend. If there was going to be a breakthrough in the trade row anytime soon then they would expect Wang to be taking a more prominent role.
"Wang Qishan would be crazy to get on a plane until there were far greater assurances there is a deal to be had and the deal would stick," said Scott Kennedy, deputy director of the Freeman Chair in China Studies at the Center for Strategic and International Studies in Washington.
TRUMP'S LATEST THREAT
One source with knowledge of Wang's meetings with US business leaders said the vice president is only going to get involved when "he can have a clear view of how he can negotiate a solid outcome." When there is something to be negotiated, Wang will probably insert himself in some way, this person said.
Neither the foreign ministry nor the cabinet's spokesman's office responded to a request for comment on Wang and his role in the US trade dispute. There is no public contact information for the vice president's office.
The last round of trade talks with Washington, led for China by Vice Premier Liu He, failed to head off a US decision to impose punitive tariffs on $34 billion of Chinese imports on Friday, with another $16 billion of goods to be targeted in a second phase. China retaliated with its own increased tariffs on $34 billion of US imports to China.
Perhaps most worrying of all for China, Trump warned the US administration may ultimately target more than $500 billion worth of Chinese goods, or roughly the total amount that the United States imported from China last year.
China has indicated it will respond with its own measures against the US each time Washington ratchets up the tariffs.
Wang's diplomacy has been low-key and behind the scenes, and there is no sign he has lost his status as a key decision maker and political player, diplomats say.
A smoker who is 70 this month, Wang is more senior than both the Chinese government's most senior diplomat, State Councillor Wang Yi, and Politburo member Yang Jiechi, who heads the Communist Party's foreign affairs commission.
Unlike the urbane, Harvard-educated Vice Premier Liu, Wang does not speak English, though he has a penchant for no-nonsense, direct talk behind closed doors, those who have seen him in action say.
CLOSE TO XI
A senior Western diplomat said Beijing appeared to be reluctant for Wang to get involved after Liu had the rug pulled out from under him by Trump's reneging on a previously agreed "consensus" to resolve the trade spat in May.
Wang is extremely close to President Xi Jinping and reports directly to him, meaning if a similar thing had happened to Wang it would be seen as a personal snub to Xi, the diplomat said.
"You can embarrass the vice premier but not the vice president," the diplomat said, speaking on condition of anonymity.
Beijing has struggled to work out what Washington really wants, especially given the US trade negotiating team has been split between those who tend to favour free trade and those who are more protectionist, a source with ties to the Chinese leadership told Reuters. This has led to confusing and sometimes contradictory statements from different officials."It's reneging on one's words," said the source, quoting a saying attributed to ancient Chinese philosopher Mencius that state media has increasingly used to refer to the US administration's struggle to give a single unified message.