This is a long, extensive article on the Darfur crisis in Sudan and the sinister role of oil.

The Darfurian genocide has resulted in deaths of hundreds of thousands and the forced migration of millions to refugee camps across the border in Chad.
The author states that oil is the main reason for inactivity by the US who do not want to risk losing access to precious oil in Sudan, which they would if they imposed sanctions on it.
As well, the long-running civil war between the government and the oppressed South has only recently been ended with a tense peace agreement so the US is now eager to move in as have oil companies from other countries.