America cannot defeat China. America can starve China to the negotiation table.
China, in the midst of its industrialization, is reminiscent of Japan at the beginning of the 20th Century. They consume more resources than they can produce domestically. China recognizes this as a weakness, hence its hawkish policies towards the South China Sea's resources (oil) and its acquisition of American agricultural resources (former Swift meats).
A war against China will need to be a seige war of attrition to starve it of resources and to encourage it to seek armistice, similar to Japan in Summer 1945. America and its allies defeated Germany. Japan surrendered. China will not be defeated, but they may capitulate if it is in their self-interest.