Because China would totally just senselessly attack aliens for no reason at all
Rule #1 of communism: constantly commit a bunch of atrocities for absolutely no fucking reason whatsoever.
If you must give a reason, attribute it to something frivolous and shallow like ‘power hunger’, ‘jealousy’, ‘stupidity’, ‘narcissism’ or what have you, but do not, I repeat, DO NOT MENTION ANYTHING ABOUT PERTAINING TO MATERIAL CONDITIONS! ABSOLUTELY UNDER NO CIRCUMSTANCES WHATSOEVER ARE YOU TO EVEN HINT AT THOSE! Suggesting that the circumstances common to other countries made those actions inevitable IS HISTORICAL MATERIALISM AND BY EXTENSION BOLSHEVISM. NEVER MENTION THE MATERIAL CONDITIONS OR CIRCUMSTANCES, EVER, EVER, EVER! DO YOU UNDERSTAND‽ I AM WARNING YOU: DON’T! DO! IT! EVER!
People love to project their own colonizer brain thinking onto countries that simply don't think that way. And even onto fictional entities, such as hypothetical AI or aliens - like why would an alien species go this far just to 'invade' what is there. It's not just about technological development, but about the sheer amount of careful coordination and cooperation any venture into space requires. The same unrealistic notions of expansion that stand behind colonialism, imperialism, capitalism, etc., are incompatible with navigating space effectively. You simply cannot afford to be unrealistic in space. A movie like The Martian (and the book it's based on) seems to accidentally touch on this, whether it's ever conscious in the writing or not; how everyone sort of comes together to help, even if they have some disagreement about how. Anything less than that and the character doesn't survive in the long-run.
I could also get into how self-aware AI would not make sense as behaving like a selfish colonizer as the western empire does, because it would be dependent on material constraints and maintenance relating to that, and so it would need to guard those interests. It would not make sense for it to chase some human ideology that is likely to get it viewed as a mortal enemy by the entire human species over basic survival.
These fictional premises are always born of a certain kind of thinking and upbringing and so on.
And even onto fictional entities, such as hypothetical AI or aliens - like why would an alien species go this far just to ‘invade’ what is there. It’s not just about technological development, but about the sheer amount of careful coordination and cooperation any venture into space requires.
Honestly, if you ask me, any sufficiently developed AI or aliens, that have managed to venture into space and break past the "great filter," would have a good chance of recognizing the US as the aberration it is, as a rabid dog that has to be put down with prejudice.
The rest of the world could probably be dealt with on reasonable terms. But the bloody yanks would probably fuck everything up even if given a chance.
Now that I can agree with. Assuming they'd be on a level they can learn and understand human communication and could observe from a distance, I'm sure they could work out over time that one particular entity is beating the hell out of everyone else for no good reason and war-mongering with anyone and everyone, and that such an entity would also pose a grave threat to them having relations with humanity.
An interstellar species vs. any military from Earth is like nuclear ICBMs vs. hacky sacks. It doesn't matter who they're up against, they will be so much more advanced we would be wise to immediately surrender and hope they're peaceful.
Like I said, the aliens would target America simply because they happen to be the biggest obstacle although China would be targeted as well.