A panda that had been living at a zoo in Tennessee is being sent back to China — and the vibes are not great. The bear is sick and some in China are accusing the US of failing to properly care for the prized panda. While pandas have long been used as a form of soft diplomacy by China, recalled bears reveal the rocky relationships between China and other countries. The World’s Marco Werman discusses the history and present of panda diplomacy with environmental journalist Gloria Dickie, whose new book is called “Eight Bears: Mythic Past and Imperiled Future.”