The key to it all is the fiat currency for trading oil. Under an OPEC agreement, all oil has been traded in US dollars since 1971 (after the dropping of the gold standard) which makes the US dollar the de facto major international trading currency. If other nations have to hoard dollars to buy oil, then they want to use that hoard for other trading too. This fact gives America a huge trading advantage and helps make it the dominant economy in the world.
As an economic bloc, the European Union is the only challenger to the USA's economic position, and it created the euro to challenge the dollar in international markets. However, the EU is not yet united behind the euro -- there is a lot of jingoistic national politics involved, not least in Britain -- and in any case, so long as nations throughout the world must hoard dollars to buy oil, the euro can make only very limited inroads into the dollar's dominance.
In 1999, Iraq, with the world's second largest oil reserves, switched to trading its oil in euros. American analysts fell about laughing; Iraq had just made a mistake that was going to beggar the nation. But two years on, alarm bells were sounding; the euro was rising against the dollar, Iraq had given itself a huge economic free kick by switching.
Iran started thinking about switching too; Venezuela, the 4th largest oil producer, began looking at it and has been cutting out the dollar by bartering oil with several nations including America's bete noir, Cuba. Russia is seeking to ramp up oil production with Europe (trading in euros) an obvious market.
The greenback's grip on oil trading and consequently on world trade in general, was under serious threat. If America did not stamp on this immediately, this economic brushfire could rapidly be fanned into a wildfire capable of consuming the US's economy and its dominance of world trade
So...maybe not a lie. Saddam was a problem for America in terms of oil. Removing him would help us