Just read them. The thing is, there are ALWAYS going to be wacked out Americans. But there aren't very many. On the other hand, there are THOUSANDS of radical Islamists. Millions, if you count world-wide. THEY are the real threat. The rest are just the same old wackos we've always had - they may someday do some damage, but it'll be minor compared to what the Jihadists can do, and it won't be coordinated.
The thing is, the few of them that exist will work hand-in-hand with the islamics, and they'll (the domestic wackos) will be highly leveraged, because they won't stick out like sore thumbs. They'll easily slip in under the radar. Like the old WWII movies, where the guy in the foxhole calls out a question for the "American" to answer -- something an American would answer correctly, but a German who speaks flawless English would flub -- these guys, even though they're fifth columnists -- will know to give the right answers, in flawless English.