Looks like a B-47 to me?
Its fictional, from Dale Brown the technothriller author. Its a converted B52 with carbon composite wings, V-tail, streamlined nose,more powerful engines and can actually dogfight and perform high G maneuvers and has a reduced radar signature, still a BUFF but now wearing a party dress, read the books!
If America needed to use 747s as an air platform it would be because other countries did the same, the Germans designed all of their passenger aircraft to serve a military role, and the Russians, well lets just say they design passenger aircraft that do military work.