Christopher Nixon Cox, grandson of former US president Richard Nixon, accompanied by his wife Andrea Catsimatidis, meets visitors to the Forbidden City in Beijing on Friday. Cox is leading a US delegation to mark the late president's historic visit to China in 1972. PHOTO BY ANDY WONG / ASSOCIATED PRESS

Kathleen McFarland, a delegation member and former member of the Nixon administration, said the visit marked "an unusual and unique thing in the history of diplomacy".

After a generation of silence, the two countries "who probably had least in common and who knew the least about each other", were able to "see the world through each other's eyes" but it was "not eye to eye, because we disagreed on so many things, and we still do", she said.

It is important today that the two countries that engineered an unprecedented development are now "at another turning point" and nobody can achieve success through confrontation with a rising power, she added.

Zhou Wenzhong, former ambassador to the US, said mutual trust and differences in bilateral relations have coexisted during the past four decades, while Washington needs to be crystal clear where the country's interests are and how will it regards China; "a partner, a competitor or a enemy?"

The key is whether Beijing and Washington can properly handle their differences and expand their common interests, said Zhou. "Despite the ups and downs, Sino-US relations have been, and will continue, heading forward as that is in the fundamental interests of the two countries."

China, acknowledged as a great power 40 years after Nixon's visit, is also stepping forward to play an important role in solving global problems facing both the US and China, including environmental protection and cyber security, said Robert McFarlane, who dealt with intelligence exchanges with China from 1973 to 1976.

Now, the US and China must focus on solving these issues through cooperation to avoid conflict and maintain stability and peace, he added.