Obama did not leave office. He moved to the Vatican. I hope Trump can spare some effort to lean on the government in VN. The officials pay a lot of attention to what the USA wants of them and this sort of thing was curtailed under Clinton and Bush who pushed hard or reforms. That all went to hell with Obama who signaled his disdain for governments he considered ow class enough to desire friendship and protection from the USA. Trump has not righted that ship there since he rose to the Presidency. I await his addition. He can publicly chastise VN and/or he can threaten trade cutbacks. Hanoi will respond and quickly.
This has been going on for years against Catholics and Buddhists who refuse to bow to the Viet Cong’s “official church” policy. Communists are evil wherever they exist.