In the intervening 12 months, Chinese leaders became infuriated when Obama met with the exiled Tibetan spiritual leader, the Dalai Lama, whom China has branded a separatist criminal, and when Washington announced plans to sell sophisticated weapons to Taiwan.

U.S. officials tried in vain to get China’s leaders in May to condemn its ally North Korea for the sinking of a South Korean warship, and then became alarmed at Beijing’s bellicose response to a September incident involving a Chinese fishing boat and a Japanese patrol ship around a group of disputed, uninhabited islands.

In between there have been disputes over trade – involving tires, car parts and chicken- and questions of whether China is manipulating its currency.

What happened over the past year, experts agree, was a case of heightened expectations on both sides crashing into realities on the ground – to the point where relations now between the United States and China are at one of the lowest points in years.