WASHINGTON (NewsNation) — For decades, the U.S. has had a scientific collaboration with China over their country’s giant pandas. However, increased tensions between the two countries have influenced the immediate return of the National Zoo’s three celebrity giant pandas.

Zoo officials told The Associated Press the adult bears, Mei Xiang and Tian Tian, and their cub Xiao Qi Ji will be returning to China in mid-November, a little earlier than originally expected.

The zoo’s exchange agreement with the Chinese government, originally brokered by President Richard Nixon 50 years ago and inspired by then-first lady Pat Nixon’s love for the animal, was set to expire Dec. 7.

The first pandas were gifted to the U.S., but after the original pandas Ling-Ling and Hsing-Hsing died in 1990 with no surviving offspring, China started renting out their pandas to America for $1 million a year, PBS reported.

Ongoing negotiations to extend the agreement haven’t produced results, amid speculation from China-watchers that Beijing is gradually pulling its pandas from Western nations due to deteriorating diplomatic relations with the U.S. and other countries.

Panda-philes around the country had circled the December date as the last chance to view the iconic bears. But the zoo, for undisclosed reasons, said the departure would happen about three weeks earlier.

“Discussions with our Chinese partner, the China Wildlife Conservation Association, to develop a future giant panda program will likely start after the current pandas have returned to China,” zoo spokesperson Annalisa Meyer said. “After 51 years of success, we remain committed to giant panda conservation. It’s our intention to have giant pandas at the Zoo again and continue our research here and conservation work in China.”

The bears have been a wildly popular attraction and an unofficial symbol of the nation’s capital for decades. Every birthday and anniversary was an occasion for public celebration, and the long-shot birth of Xiao Qi Ji in the midst of the pandemic in August 2020 drove millions of viewers to the zoo’s panda-cam.

Zoo officials say they remain hopeful they will come to a new agreement with the Chinese government.

“Right now, we are so focused on making sure that these pandas are returned to China and they return you know, happily and safely. But I can’t see beyond that,” Director of the Smithsonian’s National Zoo Brandie Smith said. “I know these animals. I know them as individuals, they mean so much to me, and I’m really going to miss them.”

The San Diego Zoo returned its pandas in 2019, and the last bear at the Memphis, Tennessee, zoo went home earlier this year. The departure of the National Zoo’s bears would mean that the only giant pandas left in America are at the Atlanta Zoo — and that loan agreement expires late next year.

Beijing currently lends out 65 pandas to 19 countries through “cooperative research programs” with a stated mission to better protect vulnerable species. The pandas return to China when they reach old age, and any cubs born in the United States are sent to China around age 3 or 4.

The pandas will endure a 19-hour journey to Chengdu, China, on a FedEx airplane. Smith said their departure back home is something that they have been preparing for her entire career with them.

The Associated Press contributed to this report.