[Zap]

I believe that there are extremists who are so far gone that you will never reach them. They will be determined to have their Jihad and nothing anyone can say will deter them.
There are also those on the fringes. These are the disenfranchised youth, who are very easily swayed. The above extremists use US acts like Afghanistan and Iraq as a recruiting tool to lure in the young Muslims that walk that fine line.
So, while the extremists have always been there and probably always will be, the acts of US intervention in the Middle East are making it more dangerous for the US in the long run.