If a state sponsored (funded) group wanted to attack commercial aviation I have little doubt they would have a high probability of being successful. The employee backdoor to airports is still wide open since TSA refuses to address that glaring oversight. The question has to be to what goal would this act be. Just placing a bomb on a plane has impact but nothing like hijacking several airplanes using them as guided missiles as happened on 9/11/2001. Unless the cockpit door is breach violence in the cabin will have little impact on the whole of flying. And I think that takes us to the issue of LGA's being bombs. Would the pilot surrender his aircraft if a threat of a bomb was made in flight? I would hope not. Are liquid bombs stable enough to carry on board and then make ready for use? I think TSA jumped the shark on this matter and have made flying more restricted than needed to address the issue. If Fonzi hadn't been the first to jump the shark I suspect TSA would have taken that honor.