There is, because of floating exchange rates. To buy imports, you need the currency of the country you're importing from. You get the currency by exchanging dollars for it. When we export, whoever is buying our stuff needs to buy dollars to buy our stuff. As long as exports and imports are of equal size, it balances out and the flow of currency in and out of the country are equal.
If we export more than we import, dollars will flow from the international money market into the US economy. With the supply of dollars shrinking, the price of the dollar will rise on the international money market, and will keep on rising as long as the supply is shrinking. Making it more expensive for foreigners to buy US stuff, decreasing the competitivity of US exporters and thus decreasing exports.
Whereas if imports are higher, the opposite will happen, dollars will flow from the US economy into the international money market, increasing supply and driving down prices. Making US exporters more competitive compared to other countries' exporters, making exports rise until they match the level of imports.
This is international trade 101, if you have no clue about this stuff you have no business suggesting policy, or predicting the consequences of whatever suggested policy with regards to China.