While economists and historians agree that access to and control of the access of others to important resources has throughout history been a factor in warfare and in diplomacy, oil imperialism theorists generally tend to assert that control of petroleum reserves has played an overriding role in international politics since World War I. Many critics (and some supporters) of the Gulf War and the 2003 invasion of Iraq as well as the 2011 Libyan civil war, argue that oil imperialism was a major driving force behind these conflicts. Some theories hold that access to oil defined 20th century empires and was the key to the ascendance of the United States as the world's sole superpower and explain how a transitioning country like Russia is able to obtain such rapid GDP growth (see Economy of the Soviet Union). Petrodollar theory states that the recent wars in Iraq are partly motivated by the desire to keep the US dollar as the international currency.
Critics[who?] of oil imperialism theories suggest that because the United States is the third largest oil producer, and that it has historically been the leading oil producer in the world, the United States would be unlikely to predicate its foreign policy on the acquisition of oil with such an undue focus. They point out that, relative to its consumption rate, oil is not an expensive commodity in the market.