From Energy Bulletin comes this:

Strategic Competition for the Continent of Africa (PDF)
Lieutenant Colonel Gregory C. Kane, United States Army War College
The United States is unarguably the pre-eminent nation in the world. Our economic
strength provides for a high quality of life for most of our citizens, large sums of capital for public and private investment, and the ability to field a highly capable and technically advanced military force. At the same time, the United States has become the largest debtor nation; currently some $7 trillion, has under-funded future governmental obligations, and has worldwide security commitments that stretch our military to the breaking point. In order to meet our future security requirements and sustain our pre-eminent military position, the United States must pursue a
foreign policy that ensures continued economic growth – without which, the government will be forced to reduce our commitments, cede resolution of issues to regional powers, or significantly reduce domestic governmental spending, currently politically unpalatable. And to secure growth, the United States needs to maintain access to natural resources and markets for American products. The largest underdeveloped market remaining in the world is the continent of Africa. We are not alone however, in that competition for Africa. China, a growing economic and diplomatic force in the world, has been aggressively pursuing economic goals on the continent and parlaying those economic ties into diplomatic clout. The competition for Africa has strategic implications for whichever country fails to establish or sustain access to that market.