How has the U.S. paid for the wars so far? The United States paid for past wars by raising taxes and or selling war bonds. The current wars were paid for almost entirely by borrowing. This borrowing has raised the U.S. budget deficit, increased the national debt, and had other macroeconomic effects, such as raising interest rates. The U.S. must also pay interest on the borrowed money. The interest paid on Pentagon spending alone, so far (from 2001 through FY 2011) is about $185.4 billion in constant dollars.