In the springtime of 1949 when PLA liberated Nanjing, all foreign embassies moved to Goungzhou along with Nationalist government except America, whose last ambassor John Leignton Stuart was ordered to remain in the city, trying to negotiate with CCP and to give the first formal recognition of the world to the new master of China.  But why did CCP and Mao refused the offer, please see following report at:   

https://www.toutiao.com/a6746289417884795400/

Without Mao and CCP, most likely China is still a larger "little brother" to the US just as Japan and South Korea has been since WWII.