The United States does not trade with Japan, or Mexico, or any other group. I trade with you. You trade with me. Smith trades with Jones. And so on.
Individuals trade with individuals.
Even when individuals trade with or as a group, such as a corporation, it is a meaningful grouping that itself is the result of trade. When two people trade with each other, there are facts that we can be absolutely sure of. Actually, these are but one fact stated three ways. We know these facts to be absolutely true because were they not true, the exchange would not have taken place. No kid who exchanges a candy bar for a Ken Griffy Jr. baseball card thinks he prefers the candy to the card.