But if China is gearing up for war, they wouldn’t mind weakening the dollar, treasuries and destabilizing the US financial system. Both countries appear to be decoupling trade relations.
China is a dictatorship and public opinion matters less.
It would still be very risky for them. They are still a developing nation economically - part of the BRIC (Brazil, Russia, India, and China). Brazil and Russia have natural resources they try to sell. China and India are factory nations with extremely cheap slave labor.
China needs external consumers. They also need to import a lot of food just so their people have something to eat. They can't even produce enough rice.
China is still not at the point where they can move massive numbers of troops to other places that would threaten the US. They could go nuclear - but it would be a matter of minutes before their country was made into glass. Their navy is still undersized to seek domination over a superpower.
Having said all of that - China has an enormous population of disposable men. Their one-child policy has created a country where girl babies are aborted in favor of boys. This has created an environment where millions of Chinese men will never get married and have a family. They become fodder for a Chinese war effort.