Mr Trump’s breezy style has long disconcerted China’s leaders. In the spring of 2017 he called Mr Xi so often to ask for help with North Korea that Chinese envoys eventually delivered a discreet message to American contacts. Mr Xi is “not our North Korean desk officer”, they pleaded: let underlings handle most of this.

Cambodia is a key political ally and trading partner for China in Asia. Xi is expected to meet Cambodian Prime Minster Hun Manet as the two countries celebrate 67 years of diplomatic ties.