WASHINGTON, July 19 (Xinhua) -- Chinese Ambassador Cui Tiankai on Thursday met with U.S. Deputy Secretary of State John Sullivan to discuss bilateral ties and issues of mutual concern.

At a working lunch with Sullivan, Cui said that the China-U.S. relationship is at a critical moment, and that both sides should fully implement the agreements reached by the two presidents, enhance communication, promote cooperation and properly handle differences to maintain the steady development of bilateral relations.

The Chinese diplomat reiterated China's principled position on Taiwan, and urged the U.S. side to adhere to the one-China principle and the three joint communiques and properly handle Taiwan-related issues.

Cui also exchanged views with Sullivan on the nuclear issue on the Korean Peninsula and cooperation in other fields.