Two key long-term energy trends are shifting the strategic balance between the United States and China, the world's superpower rivals in the 21st century: first, a domestic boom in U.S. shale oil and gas is dramatically boosting America's energy security; second, the frenetic and successful search for hydrocarbons in Africa is making it an increasingly crucial element in China's energy diversification strategy. America's increasing energy security and China's increased dependence on energy imports from Africa and the Middle East until well past 2040 despite its own shale discoveries will make Beijing's own increasing energy insecurity be felt even more acutely, pushing the People's Liberation Army to accelerate adoption of a "two ocean" military strategy that includes an enduring presence in the Indian Ocean as well as the Pacific Ocean.