this is a good read:
The End of Dollar Hegemony
Realizing the world was embarking on something new and mind-boggling, elite money managers, with especially strong support from U.S. authorities, struck an agreement with OPEC to price oil in U.S. dollars exclusively for all worldwide transactions. This gave the dollar a special place among world currencies and in essence “backed” the dollar with oil. In return, the U.S. promised to protect the various oil-rich kingdoms in the Persian Gulf against threat of invasion or domestic coup. This arrangement helped ignite the radical Islamic movement among those who resented our influence in the region. The arrangement gave the dollar artificial strength, with tremendous financial benefits for the United States. It allowed us to export our monetary inflation by buying oil and other goods at a great discount as dollar influence flourished.