Of course, no, in this trip for diplomatic purpose. He is a big guest of the Vietnamese government and citizens and it is a great honour for Vietnam to welcome him to the country.
However, if he visits Vietnam for personal purpose, without letting others know, using his popular passport like other US citizens, he will need a visa?
So, what about you, holders of popular US passports?
The answer is yes.
How to obtain one?
As a US citizen, you may have two ways to obtain a visa for Vietnam. They are:
Whether which option is used, you will get a valid visa for Vietnam. However, there is a big difference between these two options. While visa applied at embassy is for all traveller to Vietnam, visa on arrival is for those who travel to Vietnam by air only.
For a full comparison between these two options for Vietnam visa application, one can visit https://www.vietnam-visa.com/compare-vietnam-visa-on-arrival-and-embassy-visa/.