Spoons ponders the question of why there have not been more suicide bombers actually operating inside the US. I think he’s right, the answer being that even the nutters realise that the American public would be clamouring for the glass desert option milli-seconds later.
However, this little piece is in error:

Yeah, I think Sage and Jay have nailed it, with the exception of the implied nuclear response, which we would never do in response to anything less than a nuclear attack on a U.S. city (and most likely, not even then).

The stated position of the US is quite clear. Any attack upon the US using weapons of mass destruction will be met by a response using weapons of mass destruction. WMD’s are nuclear, chemical and biological. The only WMD the US possesses is nuclear. Thus, any chemical, biological or nuclear attack upon the US will meet with a nuclear response.
Phone up the Pentagon and ask if you don’t believe me.