Dealing with China has been less than smooth. First it's currency "manipulation" and lack of intellectual property protection, which have led US authorities looking to take some form of action - whether through its own countering actions via tariffs or through pressuring the WTO to take actions.
Now there's something else going on in China. It envolves a huge short copper position (in the hundreds of tonnes) by a trader named Liu Qibing, exept it's unknown wherther this individual actually exists or not. I'm not going to speculate here, but things smell rather fishy. Here's a link to a story on Asia Times Online that gives some possible explanations to this mystery phantom trader.