Giant pandas saying goodbye to Washington, D.C. and heading back to China

Finally, they transcended politics as symbols of cooperation between the U.S. and China. But now, the National Zoo's giant pandas are heading home. Here's Tom Costello. Daybreak in Washington, as the National Zoo's three biggest stars began their long journey home. After five decades, time has run out on the Smithsonian's Panda Exchange Program with China. It's been a hard week, and it's been a hard morning. Over the years, eight bears, including four cubs, have captivated visitors from around the world. I miss you. I really want to cuddle with you. Returning to China today, 25-year-old Mei Xiang, 26-year-old Tian Tian, and 3-year-old Xiaoqi Ji. This afternoon, all three loaded onto a FedEx Panda Express plane, complete with 255 pounds of food, for their 19-hour flight home. Giant pandas belong to China. Giant pandas also belong to the world. Their departure comes amid strained U.S.-Chinese relations. The exchange agreement signed 23 years ago expired this year. The last four in America at the Atlanta Zoo are set to return next year. I cannot imagine the National Zoo, I cannot imagine Washington, D.C., without giant pandas. And I will do everything I can to bring them back. Hoping that goodbye isn't forever. Tom Costello, NBC News, at the National Zoo.