China and America, we all know, have each other in a deadly embrace. The question of what China does next with its currency is at the top of many lists of worries for 2010.
The US-China relationship is the critical point of friction in the world economy. With China's currency tied to the dollar since the summer of 2008, and the dollar weakening last year, the chorus of complaint is understandable. While the informal peg remains, and the dollar keeps weakening, China's exporters get ever more competitive.
This explains moves toward capital controls by countries such as Brazil, and the ever nastier war of words between the US and China themselves.