Soon, neither the US nor China will have ambassadors in each other's capitals. Will it make a difference?

China's longest-serving ambassador to the United States, Cui Tiankai, is leaving Washington this week.

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China's longest-serving ambassador to the United States, Cui Tiankai, has announced he is standing down after eight years, adding another layer of uncertainty in the relationship between the two great powers.
Cui, 68, whose time in Washington spanned the presidencies of Barack Obama, Donald Trump and Joe Biden, has been witness to a profound shift in US-China relations. During his tenure, Beijing has grown increasingly confident and assertive, demanding that it is treated as an equal. Washington, on the other hand, has become wary of China's rise, seeing it as a strategic rival and potential threat to the US-led world order.
    "Relations between China and the US are at a critical crossroads, with the US engaging in a new round of restructuring in its government policy towards China, and it is facing a choice between cooperation and confrontation," Cui wrote in a farewell letter published on the embassy's website Tuesday.
      And until his yet-to-be-announced successor arrives, neither Beijing nor Washington will have a top envoy in each other's capital.
      The former US ambassador to China, Terry Branstad, left Beijing last year before the November election. Nicholas Burns, a former diplomat, is a top contender to fill the role, but the Biden administration has yet to make a formal announcement.
      The unusual diplomatic vacuum is just the latest sign of the ongoing breakdown in formal relations in what is considered the world's most important bilateral relationship.
        Under the Trump administration, tensions between the US and China flared across a range of fronts, from trade to technology, geopolitics and national defense.
        And with Biden casting China as an authoritarian rival to Western democracy, while seeking to form an alliance to counter Beijing, tensions are likely to further escalate.
        Cui, who has stayed on well past the traditional retirement age of 65, is widely seen as a rare stabilizing element in this volatile mix. He is typical of China's old-school diplomats, adept at expressing a firm stance in a moderate manner and measured tone. And that sets him apart from Beijing's younger and growing cohort of "wolf warrior" diplomats, known for their aggressive defense of China and hostile public attacks of its critics.
        In March last year, Cui famously denounced the conspiracy theory promoted by his colleague Zhao Lijian -- a foreign ministry spokesperson and the face of China's "wolf warrior" diplomacy -- that the coronavirus originated from a US military lab. "How can we believe all these crazy things?" he said in an interview with "Axios on HBO."
        Cui is widely tipped to be succeeded by Qin Gang, a career diplomat who currently serves as a deputy foreign minister responsible for overseeing European affairs. Qin is seen as a trusted aide of President Xi Jinping, having accompanied the Chinese leader on many overseas trips as his chief protocol officer.
        But unlike Cui, Qin has never been an ambassador and has no direct experience with the US.
        Before Cui was dispatched to Washington in 2013, he already had close dealings with the Obama administration during his four-year stint as the foreign vice-minister in charge of the Americas and Oceania.
        But for Qin, it is a much more difficult time to build bridges in Washington, which has taken a bipartisan hardline stance toward China.
        Under increasingly strained relations, there is very little room for the Chinese ambassador to maneuver, as all important policies and decisions will be made in Beijing. But Qin can still make a difference by not further damaging relations with inflammatory remarks, like some of China's "wolf warrior" diplomats have done in other countries.

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