It's the current account, its the difference between what country buys from the rest of the world and what it sells to the rest of the world.
It's a pretty good deal, we get oil, toyotas and imported romano cheese, they get pieces of paper with numbers on it.

And that paper is redeemable at the Chase, as in "the chase is on".

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“ The subjects of every state ought to contribute towards the support of the government, as nearly as possible, in proportion to their respective abilities; that is, in proportion to the revenue which they respectively enjoy under the protection of the state.”

Adam Smith , The Wealth of Nations 1776

"We have always known that heedless self-interest was bad morals; we know now that it is bad economics"
FDR's second Inaugural Address