"The Sino-US relationship needs the soft influence of each nation's first lady to offset negative impacts (on official occasions) and achieve balance," Yuan said.

Obama flew back to Washington on Wednesday afternoon. She called Chengdu a "beautiful city" and said she would not mind living in China.

Dignitaries enjoy panda diplomacy

Visitors to the Chengdu Research Base of Giant Panda Breeding in Sichuan province are as likely to spot visiting foreign dignitaries as rare pandas.

Established in 1987 with six sick and hungry pandas rescued from the wild, the base is now home to 128 of the animals. It is also a must-see destination for many visiting foreign dignitaries.

"In the past 10 years, 17 foreign dignitaries and their spouses have visited our base," said Pu Anming, chief of the general office.

In 2006, Robert Zoellick, then US deputy Secretary of State assigned to manage US relations with China, hugged a baby panda, Jing Jing, a six-month-old cub, on his lap.

The Washington Post commented that becoming a public panda-hugger is an eloquent endorsement of the view that engagement with Beijing was the best path for the United States, and that China's emergence as an Asian power does not have to mean conflict in the Pacific.

A month later, a trip to the panda base by John Prescott, then British deputy prime minister, was similarly relaxed. Prescott asked in jest whether it was he or Jing Jing who needed protection, quipping that the cub would not bite him as she was a vegetarian.

"Soon after holding Jing Jing on his lap, the cub covered her eyes with one hand. He lifted her hands and Jing Jing gently bit his, which made him laugh. Finally, Jing Jing raised her head and kissed his cheek," said base chief Zhang Zhihe.

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