First, those are their neighbors with which they have territorial disputes, like every other country (as borders where not there when the Earth was created, nor where they god given). Not some colonial grab, just out of pure greed, thousands of miles away, and with no prior provocation or history between the two countries.
Second, Mongols invaded and dominated China. You got your facts reversed. Ever heard of this guy, Genghis Khan?
Third, if we considered the same for the EU/US for example, we'd add the genocide of native americans, the abduction and slavery of 20+ million blacks for 4 centuries in the US South, colonial grabs and wars all over the planet (at some point 2/3rds of Earth were slaves under European colonial powers, not the inverse), tons of wars, the land grab of Mexico (California, Texas, etc), Hawaii, Phillipines, and Puerto Rico, the genocide of indigenous people of the Americas [1], and so on and so forth, plus 2 world wars, the genocide of the Jews, and the only atomic bombs to even fall (and on civillians).
Yeah, tell me again how bad China has been?
[1] https://en.wikipedia.org/wiki/Genocide_of_indigenous_peoples
Is that how it is called now?
But they are also, really, unpredictable lately. George W. Bush was reelected after(!) starting 2 wars. Donald Trump is...well... unpredictable. And I have yet to see him be ousted in 2020. Let alone what the next Donald Trump looks like.
Imagine if someone came along with the same ideas who actually knows how to get stuff done in Washington.
It's just better to be self-sufficient in anything relating to critical infrastructure. As the Americans themselves say: hope for the best, prepare for the worst.
Trump seems like a wildcard but his actions are predictable.
Only if you belive in reparations, that children and those who had no say are somehow bound by their country and ancestors.
And don't count eastern Europe.
I owe gratitude for the American soldiers who fought the Nazis - because if they hadn't done that I would live in a very different world. Probably I would not exist. So I am grateful to those people.