US President Barack Obama, left, chats with Chinese President Xi Jinping as they walk from the West Wing of the White House to a private dinner across the street at Blair House, in Washington, September 24, 2015. [Photo/Agencies]

Fan Jishe, a US studies researcher at the Chinese Academy of Social Sciences, said the kind of private, informal talk between Xi and Obama will help nurture personal trust between the two nations' leaders and give them a chance to exchange visions on their country's strategic development, which has been a key concern for many people.

"We don't usually say this, but in the past, the top leaders' meetings were much more formal and sometimes ceremonial, during which personal relationships were not easy to be established," Fan said.

"The current small-scale and face-to-face meetings allow the two leaders to talk about matters frankly and sincerely, especially regarding some topics that are not likely to be raised during formal political meetings," Fan added.