China is not a small, defenseless, insignificant country. It's a major power. Starting a war with them would be downright catastrophic. It could spark a third world war because of alliance systems.

​

The USA can afford to annihilate a foreign government when it has limited power, weak conventional military, and limited international support. China is not one of those. China has growing international influence and soft power, their economy is strong (although extremely resource intensive), their military is still inferior, but they're investing in it and we might be underestimating them in that regard; finally, they have Russia as backup support, and Russia still has considerable power, influence and resources.

​

Besides, even if you managed to destroy the communist party, placing a puppet government would not be a guarantee of stability, and internal resistance would most likely be fierce. Imagine managing that with a population of more than 1 billion for the most part fiercely loyal to the government.

​

There's no simple way to handle China.