The Smithsonian National Zoo received its first giant pandas from Beijing in 1972, and the species has been one of the zoo's biggest draws ever since. But with President Trump's trade war with China spiraling, could the U.S. be at risk of losing them?

The national zoo's agreement with China runs through December 7, 2020. Discussion about the next agreement will begin soon, a zoo spokesperson told CBS News Thursday.

There are also giant pandas currently on loan from China at Zoo Atlanta and the Memphis Zoo. There had been a pair at the San Diego Zoo, but their loan agreement ended and they returned to China in April.

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For over a year, the world's two largest economies have been ratcheting up tariffs on billions of dollars worth of goods, rattling the global economy in the process. If the trade war continues, the Washington Post raised the possibility that the contract might not be extended again and Mei Xiang and Tian Tian could be taken back to China.

The current agreement covers the zoo's two adult pandas, Mei Xiang and Tian Tian, as well as any cubs born at the zoo. One of their male cubs, Bei Bei, is already scheduled to be sent to China in the next few months.

🐼 Cue the music! #TianTian turned 22 years old today! Our Department of Nutrition Science made him a frozen 🎂 cake of diluted juice, apples, pears, cooked sweet potatoes, leaf-eater biscuits, banana and sugar cane. #PandaStory pic.twitter.com/AuvA6IUwE6 — National Zoo (@NationalZoo) August 27, 2019

According to the zoo spokesperson, no one from the Trump administration has contacted the zoo regarding the status of the pandas. But researchers are hopeful given the success of the program over the last several decades.

"Our giant panda program is based on a science conservation plan developed by our organization and partner, Chinese Wildlife and Conservation Association," the spokesperson said. "We've had great conservation success and are committed to continuing the good work with our Chinese colleagues to conserve this special species."

President and Mrs. Nixon welcomed the zoo's first two giant pandas from China in April 1972. According to a history posted on the zoo's website, Ling-Ling and Hsing-Hsing were sent to the U.S. after the Nixons' historic visit to China, when the first lady expressed interest in the animals to Chinese Premier Zhou Enlai. The pandas produced five cubs over 20 years, but none survived.

These and other pandas have been a symbol of cultural collaboration between the two nations ever since, the zoo said.

Not only did Ling-Ling and Hsing-Hsing's arrival generate "pandamonium" across the country, they also gave researchers unprecedented opportunity to study the species. The zoo has become a hub for the conservation of the vulnerable species.

Mei Xiang and Tian Tian arrived in 2000, on loan in exchange for funds and expertise on giant panda conservation in China. The Smithsonian National Zoo paid $10 million to have the pandas for 10 years, eventually extending their contracts to 2020.

Mr. Trump said China called Washington "twice" last weekend and wants "to make a deal" to end the trade war — which would presumably be good news for fans of the pandas, if it pans out.

"I think we're going to have a deal, because now we're dealing on proper terms. They understand and we understand," Mr. Trump said. "Very big things are happening with China."