China would suffer the same fate as the Soviet Union and the United States.
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You may be right, however, there is nothing stopping the Chinese from being as brutal as they want - like just killing everyone - there is no moral code to stop them and who is going to stop them should they proceed that way?
It would be a good spot to bloody their inexperienced troops as well.
The Soviets were pretty brutal, though I do imagine the Chinese could and would go further in that regard. But in the end it would suck the life out of the Chinese just as it did the Soviets. And I imagine the US would do the same thing it did when the Soviets were there - supply the Afgans, including the Taliban, with state of the art hardware. The Russians took a serious beating from the stinger missiles we supplied them.
It’s well nigh impossible to really conquer a country like that over the longer haul.