Two giant pandas bound for the National Zoo in Washington, D.C., have left the Chinese city of Chengdu for their long journey to a new home.

A cargo jet operated by FedEx is transporting the pair, both aged 3 years old, the Associated Press cited the China Wildlife Conservation Association as saying in its statement.

The pair — one female called Qing Bao and one male called Bao Li — will arrive almost a year since the last giant pandas left Washington D.C. Their move is part of an ongoing conservation project with Beijing that dates back several decades and is often informally referred to as an element in China's "panda diplomacy" with several nations that includes the United States.

First lady Jill Biden was part of a group that announced their planned arrival during a video released in late May.

The National Zoo has not issued any precise details of their arrival out of security concerns, and phone calls to the zoo went unanswered late Monday. But the zoo on social media hinted at the duo's expected Tuesday arrival in announcing that the zoo would be closed that day.

Zoo staff hope to raise $25 million to aid in giant panda conservation efforts, including greater protection of their mountain forest habitats in rural China. The zoo recently issued a fundraising demand on its website, asking for help from visitors, members and donors.

A Boeing 777 cargo jet — nicknamed the “Panda Express” — is slated to arrive via Alaska at Virginia's Dulles International Airport mid-morning on Tuesday, according to flight tracking websites that have identified a FedEx aircraft that departed from Chengdu.

According to the AP, the Chinese conservation association said that zoo officials and veterinary staff will be accompanying the animals. Medicine, water and specially prepared meals of bamboo, Chinese cornbread and carrots are also in tow.