"China-US cooperation on panda conservation will not cease, our people-to-people exchanges and subnational cooperation will not stop, and once opened, the door of China-US friendship will not be shut again," Xie said, adding that with the new round of cooperation, China and the US will work to improve the status of pandas and other rare wild animals, moving them from endangered to vulnerable, and ultimately to safe.

"China has sent the first pair of pandas to the US with the ice-breaking trip by (then) president Nixon, inspiring in many Americans a strong interest in China. A panda a day keeps the sorrow away," he added.

California Governor Gavin Newsom echoed Xie's sentiments, saying, "There's nothing I enjoy more than watching the press report on pandas."

Newsom recalled a moment when an 8-year-old girl was interviewed on TV. When the reporter asked if she knew that pandas were coming back, "she lit up and got teary-eyed".

"This is a moment about exchange and understanding," said Newsom, who earlier declared Aug 8 to be "California Panda Day".

"It's about something much deeper and richer than just the two beautiful pandas we celebrate."

Newsom reflected on the challenges of recent years, noting how people have been living in a world filled with stress, anxiety and division, often focusing on differences rather than unity.

"For me, the spirit and pride associated with today's opening of Panda Ridge represent a deeper meaning — that we not only share brief moments in life, but we've also triumphed together," he said.

San Diego Mayor Todd Gloria said Panda Ridge represents the latest chapter in the US-China story.

"Thirty years ago, the zoo — in partnership with our zookeeper friends in China — became a global leader in giant panda conservation," Gloria said. "I believe this is just the beginning of continued investments in the relationship between our countries. I extend my appreciation to President Xi for his commitment to continuing this incredible conservation effort between our two countries."

California and San Diego share a special bond with giant pandas. The San Diego Zoo was the first US institution to collaborate with China on panda conservation efforts.