TAIPEI (Taiwan News) — China’s ambassador to the U.S., Cui Tiankai (崔天凯), will be returning home after serving in the post for more than eight years.

The Chinese Embassy in the U.S. on Monday (June 21) published a farewell letter written by Cui in which he said China-U.S. relations are at a "critical crossroads" and that U.S. policy toward China "is undergoing a new round of restructuring, facing a choice between dialogue and cooperation or confrontation and conflict."

Cui suggested that overseas Chinese in the U.S. should shoulder more important responsibilities supporting Beijing's diplomacy, including “safeguarding the fundamental interests of the people of China and the United States” and “promoting world peace, stability, and prosperity.”

Cui also pointed out that he began his post in 2013, making him the longest-serving ambassador to the U.S.

There has been no official statement from China's foreign ministry as to who will take Cui’s place, but sources familiar with the matter expect Qin Gang (秦剛), a vice foreign minister, to assume the post, Reuters reported.

Qin served Chairman Xi Jinping (習近平) as chief protocol officer from 2014-2018 and was also a foreign ministry spokesperson from 2006-2010 and 2011-2014. He is known for his assertive comments defending China, Reuters wrote.