"Giant pandas belong to China. Giant pandas also belong to the world," Xu said. "China will continue to work closely with cooperation partners, including the United States, on the conservation and research of endangered species and biodiversity protection. We'll make greater contributions to the sustainable development of this planet and the friendship between people of all countries."

When the convoy arrived at the Dulles International Airport, journalists and officials had already gathered on the tarmac, expecting the final farewell moment for the cuddly cuties.

A FedEx Express Boeing 777 Freighter with a huge giant panda picture painted outside the cockpit was parked with its cargo cabin gate open, ready to load the pandas onboard and carry out the transport mission. FedEx had flown similar missions for other pandas in the United States that went back to China.

Smith gave some remarks again. "We are celebrating the success of the world's longest-running conservation program for a single species. And the more than 50 years that we have been working with these animals, giant pandas have been moved off the endangered species list," she said, receiving a big round of applause.

"Our partners in China, the Conservation and Research Center for the Giant Pandas, have been just phenomenal partnership to work with, learning to care for these species and saving them in the wild," the director added.

As the crates were being loaded onto the plane one after another, Mei Xiang tried to catch a final glimpse of Washington from the window of her crate, as if she was really saying final goodbye to the city where she had spent 23 years, and to all those who loved and would be missing her so much.

With the plane's engine roaring and the crowd cheering, the pandas embarked on their journey back to their homeland.

As part of the effort to ensure a comfortable flight for the three pandas, two keepers and a veterinarian will accompany the bears on board the plane, which is heading for the southwestern Chinese city of Chengdu. The duration of flight is expected to be about 19 hours, including a refueling stop in Anchorage, Alaska.