They're taken from thin air. The Fed just prints it.
Look at the countries that have opposed that since the beginning of the millennium: Libya and Iraq saw, ahem, “kinetic interventions”, and Iran and Venezuela are still being crushed by sanctions for daring to price their oil in Euros and/or RMB.
Have you actually looked at where the dollar has been heading, even with all of this "money printed"? Up. Way up.