The 1973 oil crisis further fixed the value of the dollar as a result of this oil shock, bringing Saudi Arabia and the OPEC countries to make a secret agreement with Washington….. This agreement provided that in exchange for Washington’s political and military protection, the OPEC countries would be required to sell oil only in dollars. The petrodollar was thus born, being a replacement for the gold-linked standard that existed prior to Nixon. Once this system was supported by OPEC members, the global demand for US petrodollars hit an all-time high. https://www.activistpost.com/2024/06/why-the-petrodollar-is-finished-now.html