A few key outside factors are chipping away at the US dollar's dominance in global trade.Getty Images The US dollar has been the world's reserve currency for decades, but its dominance is fading. Sanctions against Russia have spurred other countries into considering backup currencies for trade. US monetary policies, the strong USD, and structural shift in the global oil trade also contribute. The dollar has been the world's reserve currency since World War II, but a combination of political and economic reasons is slowly chipping away at its supremacy.Nearly 60% of international reserves are held in dollar-denominated assets, according to the International Monetary Fund.