Giant pandas are some of the world's most vulnerable and rare creatures. The United States has the most giant pandas outside China. [Photo provided to China Daily]

"Hopefully, in a few years our colleagues in China will share happy news with us that Bao Bao has become a mom," Dearie carried on.

Bao Bao, whose name means precious or treasure in Chinese, dubbed by fans as the world's cutest giant panda, was the first female born at the US National Zoo, and has won hearts of numerous Americans since her birth. Her parents Mei Xiang and Tian Tian moved to the American zoo in 2000 under a collaboration agreement between China and the United States.

From 1984, China stopped giving giant pandas as gifts abroad and began to offer pandas to nations only on a 10-year loan. According to the agreement, panda cubs born in the United States to parents on loan from China must be returned to China before they are 4 years old.

China's ambassador to the United States Cui Tiankai once wrote to The Washington Post that "it's very difficult for giant pandas to breed naturally, Chinese and Americans have been working on breeding them through artificial insemination".

US State Department also called giant pandas as "a tangible and fluffy manifestation of cooperation between the United States and China".

Giant pandas are clearly envoys of China-US friendship that endures time. Over the past four decades, as far as the pandas reached, it was always full of love and joy.