For decades, the US's greatest weapon has been its dollar which, with time, ceased being a normal currency per se, to become an actual commodity. Wars have been fought to ensure countries, like Iraq and Libya, remain committed to the dollar. Following the US invasion of Iraq in March 2003, Baghdad returned to selling its oil in US dollars. This struggle over the dominance of the dollar was also painfully felt in Venezuela which has the world's largest oil reserve, yet was reduced to abject poverty for attempting to challenge the supremacy of Washington its currency.