Beijing has been without an ambassador in Washington for more than three months, the longest period since U.S.-China relations normalized in 1979, a situation that reflects the dismal state of the nations' ties and potentially signals a serious rethink of how it engages with the U.S.

There is a broad review in Beijing...over how to handle U.S. policies seen to be increasingly adversarial, analysts say, with the three-month delay an outward manifestation of uncertainty and tactical and strategic reappraisal.

"China wants to get a sense, are you really serious about figuring out some way of turning down the heat or not," says Dimitar Gueorguiev, associate professor of political science.

"And they have reason to be suspicious on where we're going with the electoral cycle in the U.S. and how risky it is."

Read more in the South China Morning Post article, "China's longest US ambassador vacancy provides latest sign of bleak relations."