As the UK’s only giant pandas leave Edinburgh zoo , returning to their native country after a 12-year sojourn away from China, the era of panda diplomacy also looks to be coming to an end. Tian Tian and Yang Guang will board the panda express back to Sichuan less than a month after three giant pandas left the Smithsonian national zoo in Washington DC, ending the zoo’s five-decade panda programme. The homecoming of the five giant pandas in recent weeks reflects the end of long-agreed lease arrangements. Zoos typically pay between $500,000 (£395,000) and $1m a year to Beijing for the bears, which return to China in their old age. But the departures come at a moment where Beijing’s relations with the west are increasingly strained and less easily mollified by loans of cuddly endangered bears. Panda diplomacy – the term given for China leveraging the bears to improve international relations – is thought to date back to the seventh century, when the Chinese empress Wu Zetian sent two bears as a gift to Japan. China’s modern leaders have also embraced the strategy. When President Richard Nixon visited China on a landmark trip in 1972, he was followed home a few months later by a pair of pandas gifted by Mao Zedong (Nixon sent two musk oxen to China in return). In 1984, Deng Xiaoping, the Chinese leader credited with opening up China’s economy to market forces, also saw the economic potential of China’s panda population. Beijing started leasing pandas, rather than gifting them, with the stipulation that any cubs born overseas would also be the property of China. Some European nations and Qatar are among recipients in the last decade. But no new pandas have been sent to the US in 20 years. Xi Jinping commented recently that China was ready to continue the cooperation efforts with the US, but there are no known plans in the works and many are now making their way back to China as loan terms come to an end. Three pandas were returned from the Smithsonian zoo last month. The agreement for four bears at Zoo Atlanta expires next year. Cooperation on panda conservation with the UK will continue, even without any bears making the journey from China. On Thursday, Chinese state media reported China’s Giant Panda national park had signed a memorandum with the UK’s Lake District national park, Loch Lomond and the Trossachs national park. “The signing of the memorandum will further strengthen the cooperation between China and the UK in terms of resources, capabilities, willingness, and determination,” said Zhang Zhihe, the deputy director of the Chengdu bureau of the Giant Panda national park administration. “The national giant panda conservation is China’s first group of national parks, with the protection of wild giant panda population and their habitats as well as landscape conservation as its core, and it has become an important window to showcase China’s image,” said Zhang.