This is a good article. It reviews the increasingly tough stance of the U.S. vs. China and the signs of potential protectionism if China doesn’t play ball.
Obama is becoming more assertive with China in order to demonstrate a record of toughness with the communist country and counter Romney’s tough talk come election time. That’s me reading betweens the lines.
It seems that action is accompanying rhetoric this time around and marks an escalation of the issue.