In 1973 President Nixon asked King Faisal of Saudi Arabia to accept only US dollars as payment for oil and to invest any excess profits in US Treasury bonds, notes, and bills. In return Nixon offered military protection for Saudi oil fields. The same offer was extended to each of the world's key oil producing countries, and by 1975 every member of OPEC had agreed to only sell oil in U.S. dollars.
The act of moving the dollar off of gold and tying it to foreign oil instantly forced every oil importing country in the world to start maintaining a constant supply of Federal Reserve paper, and to get that paper they would have to send real, physical goods to America.
This was the birth of the Petrodollar, Paper dollars went out, everything America needed came in and the United States got very, very rich as a result. It was largest financial con in recorded history.
Through 70s and the 80s the U.S. used the financial power gained by the petrodollar arrangement to build the most powerful military in the world, and when the Soviet Union collapsed in 1991 the United States was left with no rival.
Many hoped that at this point the U.S would start to reduce its military presence across the world, and that a new era of peace and stability would follow...
Unfortunately there were those in high places which had other ideas
Within that same year the U.S. invaded Iraq in the first Gulf war, and after crushing the Iraqi military and destroying their infrastructure, crippling sanctions were established which prevented that infrastructure from being rebuilt. These sanctions which were initiated by Bush senior and sustained throughout the entire Clinton administration lasted over a decade and were estimated to have killed over 500,000 children. The Clinton administration was fully aware of these figures.
In a final act of resistance Iraq began selling it's oil exclusively in Euros November of 2000.
This was a direct attack on the dollar and on U.S. financial dominance, and it wasn't going to be tolerated.
In response the U.S. government, with the assistance of the main stream media began to build up a massive propaganda campaign claiming that Iraq had weapons of mass destruction and was planning to use them. In 2003 the U.S. invaded, and once they had control of the country oil sales were immediately switched back to dollars.