China's new ambassador arrives in US as 'severe challenges' fester

China's new ambassador to the United States has arrived in the country, vowing to shoulder the "heavy responsibility" of a superpower relationship that is "facing severe challenges".

Xie Feng, a career diplomat with extensive experience in Washington, arrived in New York on Tuesday (23 May), Beijing's embassy in the US said in a statement.

He replaces Qin Gang, who left his post earlier this year to serve as China's foreign minister.

"At present, Sino-US relations are encountering serious difficulties and facing severe challenges," Xie told reporters at the airport, according to a statement on the embassy's website.

"I feel both a glorious sense of mission and a heavy responsibility. My colleagues and I will face up to difficulties, fulfil our responsibilities and live up to our mission."

The US ambassador to China, Nicholas Burns, said Wednesday he had held a "farewell dinner" with Xie "as we manage the ever-challenging US-China relationship".

"I look forward to working with him in his new role," Burns said on Twitter.

According to an official government biography, 59-year-old Xie hails from the wealthy eastern province of Jiangsu and holds a master's degree in engineering.

He has worked in the foreign service since at least 1986 and spent much of the 1990s rising through the ranks of the ministry's bureau for North American affairs.

He served two stints in China's outpost in Washington during the following decade, before becoming ambassador to Indonesia.

Most recently, Xie worked as commissioner of Beijing's foreign ministry in Hong Kong, and as vice minister of foreign affairs.

Relations between China and the US have become fraught in recent years, with tensions flaring over trade, technology, human rights and other issues.

A recent flashpoint has been high-end microchips, with Beijing saying on Sunday that US semiconductor giant Micron had failed a national security review and would not be allowed to sell to operators of "critical information infrastructure".

The announcement came after Washington and its allies took measures in recent months that China claimed were designed to restrict its ability to purchase or manufacture cutting-edge chips and curb its rising global power.

Beijing this month also sentenced American citizen John Shing-wan Leung, 78, to life in prison for espionage, but disclosed few details about the case.