President Obama, from his State of the Union address:
I will go anywhere in the world to open new markets for American products. And I will not stand by when our competitors don’t play by the rules. We’ve brought trade cases against China at nearly twice the rate as the last administration – and it’s made a difference.
Just how much of a difference? Hard to say, but it hasn't stopped the U.S. trade deficit with China from keeping a sharp upward trend since Obama took office. Data from the U.S. Census Bureau:
