If u. s. businesses and individuals buy more goods from abroad than they sell (more imports than exports), the u. s. is running a foreign trade , which must be financed. this generally means that the u. s. borrows from nations with export . the larger the trade , the higher the tendency to borrow, so u. s. interest rates become highly dependent on interest rate levels abroad. consequently, this interdependency the fed's ability to use monetary policy to control u. s. economic activity.