When US President Donald Trump met Vietnamese Prime Minister Nguyen Xuan Phuc in May, he sent a clear message: by patting the backs of authoritarian leaders, the US is complicit in Vietnams rights abuses.

Trump is no stranger to brushing shoulders with autocratic leaders. Allegations of cosying up to Russian President Vladimir Putin aside, he has praised Philippine President Rodrigo Duterte, Egyptian leader Abdel-Fattah el-Sisi and Turkish President Recep Tayyip Erdogan.

But Trump extending hands to Vietnams leader is perhaps unique given the two countries past animosity, and particularly since Hanois crackdown on opposition voices, seen by many as its toughest in years.