China has been buying up the United States debt for some time. This makes them dangerous as they make money off of our prosperity. They have more people in their country than we do which gives them the opportunity to become more technologically advanced. They are our biggest international threat.
China currently holds a lot of American debt. In addition, China and the USA have created a lot of global business deals that are helping the American economy get back on track. China also acts as an emissary to the unpredictable and tumultuous regime of North Korea. For all of these reasons, to consider China America's number one adversary at this point in time is not wise.