I recommend on reading up on the history of South America. It might be eye opening, pretty much every country had at some point a military dictatorship/junta killing their people, established with the help of the CIA. The USA has the clear "good guys" is by far not so straight forward. That is not to say that Russia or China are.

And then we could argue the whole premise of "we have to do it because the others are doing it" which can be used to justify everything.