If the 20th century was America's century, many say the 21st will be China's.
It's early still to make that call. But there's no mistaking the tension between Washington and Beijing, especially over who calls the shots in the Asia-Pacific region.
US Secretary of State, Hillary Clinton, went to Beijing on Tuesday to press China about its many territorial disputes in the South and East China Seas.
At stake are large suspected reserves of oil and gas under the disputed seas.
She was traveling from Indonesia, where she called on Asian nations to present a united front against China. Clinton also proposed a binding code of conduct among them and China to prevent the risk of confrontation.
The World's Beijing correspondent, Mary Kay Magistad, says China is not happy about that.