Is it normal i feel frustrated that americans can get away with anything?

Sorry if my english is not good.

I am from vietnam and my granparent was exposed to agent orange during the US invasion. My mother's older brother died from a cancer tumor when he was 31, her younger brother had a deformed hand since born and could not use it. Doctors said I have increasing risk of cancer especially since there are parts of the land near town that are still contaminated with the agent. Only now 40 years later are americans starting to clean up their own thing. They never were punished by UN or anything like that, even though they started the war and more than a million vietnamese civilians have been attacked by agent orange.

I was very frustrated so I started researching history, and I discovered that americans have been doing stuff like this for a long time and always get away with it, no consequences. The japanese leaders were executed during war but no one was punished for the civilians fried to a crisp by the atom. Native indian americans are almost completely dead and killed off yet no one mentions this in movies and stuff, even though historians say that more died that in the holocaust of jewish people. Even now I hear about americans complaining about iran, but apparently the only reason that there is islamists in power is because US removed previous head of state in coup in 1953. Even obama gets the nobel peace prize and orders drone attacks that kill civilians every week.

So why do US always get away with anything, there is no justice. The winners write history I guess. Am I right to feel this way?