What the OP said is true. Countries do trade USD with each other, but considered as a group the net effect is that countries can only: >send it back to you by

What the OP said is true. Countries do trade USD with each other, but considered as a group the net effect is that countries can only: >send it back to you by buying things from you, lending it to you, or making direct equity investments in your companies. That's true whether one foreign country exists or 10,000.