Similarly, Germany was the de facto enemy of the Ally aligned world in the 40s and only a few short decades later best friends with most.
You can identify countless similar atrocities in US history after which relations stabilized within a few years.
Most in life are short term oriented and it's rare that these things produce lasting effects on perception.
Does anyone care or even remotely think about what Bush did as president 20 years ago? Some politically oriented and historically minded folks yes, 99% no.
They really have to be long lasting and persistent transgressions to produce generational distrust e.g. Japan invading China/Korea many times over the last few hundred years.
However the new gen seems far less concerned about this too.
Given Trump's larger than life character/ego/presence, it's more likely that anything he does will be attributed to him instead of the country as a whole. Which makes his actions perhaps even less impactful than a more neutral presenting president doing the same.