Here's the original article. I think you'll find that Franks didn't quite say what others have claimed he said. It was more along the lines of "Another attack and the American people just might get gung-ho for a more militaristic government, and I don't think that's a good thing," not "One more attack and the Pentagon's going to take over the White House."
http://www.cigaraficionado.com/Cigar/CA_Profiles/People_Profile/0,2540,201,00.html