The US government being "interested" in something doesn't mean it can actually do anything. Just look at the MegaUpload case, for example. MegaUpload wasn't based in the U.S, didn't do business in the US and as a result the US government can't actually do anything about it.
What?
http://en.wikipedia.org/wiki/MegauploadProbably shouldn't underestimate the reach of US authorities. They can easily get to companies or people e.g. through the banks they use, their relationship with local regulators, etc.