California plays bridging role in boosting relationship

Zhang said subnational cooperation between California and regions in China plays a major bridging role between the two countries, especially at a time when China-US cooperation has hit new lows, such as during the Donald Trump administration.

The conciliatory role subnational relationships play in enhancing country-to-country ties was endorsed by California. The statement from Newsom's office noted climate cooperation as an area of alignment that may "open the door to diplomacy".

"Continuing our partnership with China on climate is a way of keeping lines of communication open so that we can continue engaging on a host of issues," it said.

During his trip, the governor toured the Great Wall with Nicholas Burns, the US ambassador to China, according to Newsom's office.

The duo discussed the importance of the US relationship with China, how the subnational partnership can help ease national tensions, and areas of cooperation between the two countries, including climate action, economic development and tourism.