It’s called “panda diplomacy” and it’s thought to have started as early as the Tang Dynasty in the 7th century when Empress Wu Zeitan sent a pair of bears (believed to be pandas) to Japan. This Chinese policy of sending pandas as diplomat gifts was revived in 1941, on the eve of the United States entering World War II, when Beijing sent two cuddly black-and-whites to the Bronx Zoo as a “thank you” gift. Chairman Mao frequently engaged in panda diplomacy in the 1950s, sending bears as gifts to China’s communist allies (such as North Korea and the Soviet Union).

Two months after Richard Nixon’s landmark trip to China in 1972, which ended 25 years of isolation and tension between the United States and the People’s Republic, the president and his wife, Pat, greeted the adorable 18-month-old pair named Hsing-Hsing and Ling-Ling. This gift from Chinese Premier Zhou Enlai created a nationwide “Panda-Monium,” causing American zoos from the Bronx to San Diego to fiercely lobby the White House to become the pandas’ new home. In the end the Washington, D.C.’s National Zoo won, and the two celebrities received over 20,000 visitors on their first day on display. The following Sunday, 75,000 people flooded the zoo, waiting in a quarter-mile-long line to see America’s newest sensations, who graced magazine covers and proved to be an economic boon for producers of toys and stuffed animals. In return, the U.S. government sent China a pair of musk oxen, Milton and Mathilda—I think we all know who got the short end of that stick.

Hsing-Hsing and Ling-Ling had five cubs while at the National Zoo, none of which lived longer than a few days. Ling-Ling died suddenly from heart failure in December 1992, at the age of 23 (at the time she was the oldest panda living in captivity outside China), and Hsing-Hsing was euthanized in November 1999, at the age of 28, due to kidney failure.

This exchange was seen as so successful it inspired British Prime Minister Edward Heath to ask for a panda loan during his 1974 visit to China. Chia-Chia and Ching-Ching arrived at their new digs, the London Zoo, a few weeks later.

The tradition saw a significant shift in 1984 when China amended its panda protocols. Moving forward, the animals would only be sent out on 10-year loans, would require payment of a standard annual fee (for the U.S. it was $1 million) and decreed that all cubs birthed from loaned pandas were Chinese citizens, regardless of place of birth. The U.S., in turn, shifted its acceptance policy in 1998, only allowing a panda to reside in the States if more than half of its annual fee was given to conservation efforts for wild pandas and their habitats.

In 2008, a devastating earthquake rippled across China’s Sichuan province, destroying 67 percent of China’s wild panda habitats. With its largest and most prestigious conservation center destroyed, China needed to find foster homes for all 60 of its surviving residents. This natural disaster, combined with what appeared to be another shift in panda policy (China now said they would only send pandas to countries for breeding and biological research), caused some to note that China’s loans seemed to be coinciding with trade deals for valuable resources and technology. Was there a panda payoff underway? For example, the Edinburgh Zoo received two pandas in 2011 (the first to arrive in the United Kingdom in 17 years). Shortly after the exchange, however, trade deals were signed between the two nations for salmon, renewable energy technology and Lan Rover vehicles. Norway (who had recently given the Nobel Peace Prize to jailed Chinese dissident Liu Xiaobo) lost its long-standing salmon deal with China. Despite the new established goals of biological research and reproduction, Hong Kong received two pandas in 2007 as a gift to mark the 10th anniversary of the handover from British rule. But this was considered an exception to the rule, a gift between brothers.

Being entrusted with these adorable, vulnerable (downgraded from “endangered” in 2016) creatures can symbolize the blossoming of new international friendships. The tragic and mind-boggling loss of Malaysia Airlines Flight 370 exacerbated tensions between China and Malaysia. The long-planned arrival of Feng Yi and Fu Wa in 2014 (two months after MH370 went missing) was seen as healing the relationship between two grieving nations after China had openly chastised Malaysia for how they handled the disaster.

You would be hard-pressed to find someone who couldn’t be won over by the antics of a panda—but they exist. Taiwan managed to turn the other cheek to the bamboo-loving diplomats for nearly three years (not surprising considering decades of tension with mainland China). In the end, however, with a change of government in 2008, they couldn’t hold out against the fuzzy power any longer and Taipei accepted Tuan Tuan and Yuan Yuan. These two 4-year-olds created “Panda-mania” when they arrived that December, becoming instant celebrities. Tuan Tuan and Yuan Yuan have produced one cub (through artificial insemination), Yuan Zai. Perhaps some nations are right in resisting the cuddly animals, as we are reminded time and time again that pandas can be mean, vicious creatures (but when provoked, aren’t we all?) who cost a lot of money to keep and breed. Some even say there is a “panda curse” where world leaders who receive pandas end up forced out of office (Nixon, Edward Heath, Japan’s Kakuei Tanaka).

China isn’t playing coy about its panda diplomacy. In fact, the Chinese ambassador to the United States Cui Tiankai wrote in a 2013 op-ed published in the Washington Post, “there are actually two Chinese ambassadors in Washington: me and the panda cub at the National Zoo.”