Anyone can start a thread, not just Americans. I have been following the McCann case in the UK, but I'm American. I found it while I was reading up on the Pricess Diana inquiry, and I have been on some forums where I was one of the few Americans there, but no one got in my way most of the time. I got banned from a few, but got banned from a few on American boards. They don't like unpopular politics and the mods always defend their point of view.
It would be nice to see posts about news overseas.