Secondly, this dollar-to-gold system requires the stability of the dollar. At that time, the background was the outbreak of the Vietnam War, the United States fell into the quagmire of war, the fiscal deficit widened, the credibility of the United States was affected, and several dollar crises broke out. Countries began to sell dollars and snap up gold, which led to the skyrocketing price of gold, and the dollar could no longer be linked to gold. This is the direct cause.
After the disintegration of the Bretton Woods system, foreign exchange mainly in US dollars was used as international reserves for a period of time, mainly because of the special political position of the United States in the world and the improvement of the American economy, which led to the rise of the credibility of the US dollar, while trade liberalization needed a currency as the settlement currency, and only the US dollar could play this role at this time.