Vietnam already let go of its animosity for the US a decade ago, all under the effort of 1 ex-POW named John McCain, we erected a memorial for him and he's widely regarded as a national hero. I can tell you any US citizen will be welcomed in here with open arms. If a somali copycat get shanked in here, it would have absolutely 0 to do with him being an US citizen and more of us being open to stabbing and slicing.
The height of US-Vietnam relation was during Obama regime, when he came here, people literally grovelled at his feet and begged for his scraps. The US wasn't stupid (before trump), they already tried influencing and taking Vietnam under its wing many years ago to check the growth of China.
But it went from "strategic partnership" into "taking care of a baby" after trump is elected. And I have 0 faith our impromptu babysitters can sooth of his current tariff tantrum. Our new president himself is already showing a lot of signs of dictatorship, he's already half way done at consolidating all governing prowess into the hands of the military.