NEW YORK, May 23 (Reuters) - China's new ambassador to Washington Xie Feng said on Tuesday that he will seek to enhance China-U.S. cooperation, but that relations face serious challenges.

"I have come here to safeguard China's interest. This is my sacred responsibility," Xie told reporters after landing at New York City's John F. Kennedy International Airport.

"I'm also the envoy of Chinese people, so I've come here to enhance China-U.S. exchanges and cooperation," said Xie, who has garnered a reputation for blunt rebukes of U.S. actions as ties between the strategic rivals have deteriorated over issues ranging from Taiwan to trade.

Xie, 59, most recently served as a vice foreign minister charged with overseeing policy toward the U.S.

The two countries' relations face "serious difficulties and challenges," Xie said in his brief remarks before departing the airport and boarding a van. Chinese officials said he would be driven to Washington.

A fluent English speaker who was previously posted twice to China's Washington embassy, Xie lodged China's formal denunciation in February accusing Washington of "obstinately" shooting down what it suspected was a Chinese spy balloon after its flight over the United States spurred a diplomatic crisis.

Beijing has said it was a civilian airship.

State Department spokesperson Matthew Miller said the U.S. welcomed Xie's arrival.

"We look forward to working with the ambassador designate and his team. We remain committed, as we said on a number of occasions, to maintain channels of communication with the PRC (People's Republic of China) to responsibly manage competition," Miller said.

Xie has taken a confrontational tone in past meetings with Biden administration officials, including when hosting Deputy Secretary of State Wendy Sherman in 2021 in Tianjin, where he issued a long list of demands for the U.S. to improve ties while accusing Washington of creating an "imaginary enemy" in China.

Nonetheless, Xie's arrival at the embassy post, which has been vacant since his predecessor Qin Gang was elevated to foreign minister late last year, could help Beijing parry criticism that it has ignored the Biden administration's calls for increased engagement.

Qin told Washington's envoy to Beijing this month that it was essential to stabilize relations, and U.S. President Joe Biden – who expressed a desire to speak with Chinese leader Xi Jinping after the downing of the balloon – said on Sunday that he expected more U.S.-China talks "very shortly."

Bonnie Glaser, an Asia expert at the German Marshall Fund of the United States, said Xie, as an experienced diplomat well-acquainted with U.S. policymakers, was capable of facilitating better communication "if he chooses to do so."

"The decision to finally send Xie Feng appears to be part of this effort to prevent a spiraling deterioration of bilateral ties," Glaser said.