China is invested in the US, they own about $1 trillion in US government debt and we run a $350 billion annual trade deficit with them. That debt props up the Yuan, if the US dollar plunges in value, Chinese good become more expensive, thus it is in their best interests to have a healthy US economy so we keep buying their stuff at relatively low prices. It is not in their best interest to have our economy tank. They understand the value of their relationship with the US, it's a mistake to think that they don't.
China has now become a net importer of food, in other words they can't feed themselves on their own domestic production. We have the world's best transportation network to get farm products moved to market including getting it to China. They are dependent on us to make up that food shortfall. There's also oil and coal which China imports.
No need to be scared of the Chinese, in some ways we have them by the short hairs. We need to really work on our trade relationship with China, it's time for a change.