China and the United States should work together to jointly implement the important common understandings reached by the two heads of state, and maintain the momentum of stable development in bilateral economic and trade ties, Guo Jiakun, Chinese Foreign Ministry spokesperson, said on Friday.

Guo made the remarks in response to questions over US Trade Representative Jamieson Greer's comments on the ties.

According to media reports, Greer said on Thursday that he was "optimistic" about the stability in US-China ties.