It occurs to me that the current stricter security for passengers and flying in general is very like the Maginot Line in France. You remember the Maginot Line, right? After WWI, the French built a very impressive defensive line along their border with Germany to prevent another invasion from them. Problem was that Germany did an end run around it for WWII. They never actually broke the line. This is not to say security shouldn't have been tightened, just that I doubt terrorists will use the same tactic again. An advantage (or problem) with guerrilla fighters is that the specifics of tactics are fluid depending on opportunity and targets. Gee, that sounds like I've really thought about this problem but it just makes sense to me.