The US-born giant panda Bei Bei has left his home at Washington's National Zoo for China.
Bei Bei will travel on a specially equipped flight from Washington to Chengdu, accompanied by his keeper and a veterinarian.
The giant panda turned four years - the age when all pandas born outside return to China under their breeding agreements.
"Today is bittersweet. We've cared for Bei Bei, and along with millions, watched him grow into a true ambassador for his species," said zoo director Steve Monfort.
"We look forward to continuing our 47-year giant panda conservation program and collaboration with Chinese colleagues to study, care for and help save the giant panda and its native habitat."
Zoo officials said they had prepared a special stash of treats for him: 30 kilos of bamboo, two pounds of apples and pears, two pounds of cooked sweet potatoes, two bags of biscuits and water.
Trump-Putin summit cancelled, FT reports
Hurricane Melissa leaves 49 dead in Caribbean, churns north
King Charles strips brother Andrew of titles and his mansion
Vietnam flood death toll rises to 13, with 11 others missing
US grants India six-month sanctions waiver to run Iran's Chabahar port
