In recent research related to the US dollar's status as global reserve currency, I came across a fascinating excerpts from a 2015 speech by Qiao Liang, Major-General of China's People's Liberation Army, strategist, and author. Qiao has concluded that the US enforces the global reserve status of the dollar by any means, including war. Even if you don't find this theory particularly credible, it's still noteworthy that highly placed Chinese officials give it serious consideration.
Here's Qiao on the Iraq war:
Why did the Americans fight a war in Iraq? Many people would answer,For oil.However, did the Americans truly fight for oil? No. If they indeed fought for oil, why didn't they take a single barrel of oil out of Iraq? Also, the crude oil price jumped to US$149 a barrel after the war from a pre-war price of $38 a barrel. The American people didn't get a low oil price after its army occupied Iraq. Therefore, the U.S. fought the war not for oil, but for the dollar. Why? The reason was simple. To control the world, the U.S. needed the whole world to use the dollar. It was a great move in 1973 to force Saudi Arabia and other OPEC countries to install the dollar as the settlement currency for oil trades. Once you understand that, you can understand why the U.S. fought a war in an oil producing country. The direct result of fighting a war in an oil producing country was to increase the price oil. Once the oil price shot up, the demand for the dollar also went up. . . . I also want to tell everyone, the U.S.'s war in Iraq was not only for that goal. It was also to keep the dollar's hegemony. Saddam didn't support terrorists or Al-Qaeda, nor did it have weapons of mass destruction. But why was he still hung? It was because he played a game between the U.S. and EU. After the euro was created in 1999, he announced that Iraq's oil trade would be settled in euros. This angered the Americans, especially when many other countries followed suit. Russian President Putin, Iranian President Ahmadinejad, and Venezuelan President Hugo Chavez all made the same announcement. How could the Americans accept this? Some people may think what I said was a fairy tale. Let's take a look at what the America did after it won the Iraq War. Before they arrested Saddam, the Americans rushed to form the temporary Iraqi government. The first order that the temporary government published was to announce that the Iraqi oil trade switched from the euro back to the dollar for settlement. This showed that America was fighting for its dollar.