While some people devote their mental energy to going insane with fear and retreat into the belief that any problem can be solved with enough money and Anglo-Saxon masculine Toughness, the rest of the world begins to realize that living with the permanent, inescapable threat of terrorism is just the new normal. We are seeing why terrorism is so effective and so popular as a tactic – it works. It creates a state of constant fear driven home by the realization that it can't be stopped. It can be fought against, curtailed, and kept in check, but it can never be stopped. As long as there are a handful of people who can get their hands on guns (and god knows anyone can) and think of some brilliant strategy on the order of, "Let's go to the mall / airport / train station and shoot a bunch of people!", terrorism will continue. There is no way around it. High tech, expensive plots can be foiled because there are so many things that have to go right to make them work. Low cost, crude plots like the kind seen in Paris, Orlando, or Istanbul. It's some guys with homemade bombs and cheap guns. No perversion of the balance between freedom and security can account for that, provided they're not dumb enough to do things like call information and ask for the number for ISIS.
You can kill as many terrorists as you want, pass a bunch of laws that create the illusion of security, and vote for as many right-wing xenophobic ultra-nationalists as you can find, and ultimately it won't bring the one thing everyone seeks: peace of mind. The feeling that one can live and work and travel and play without the risk of some idiot with a small arsenal bursting in and blowing himself up or firing off a few hundred rounds. The risks can be minimized but never eliminated, which is slowly driving older, more reactionary cliques in the Western world insane. This isn't The Commies who could be kept at bay with Deterrence and saber-rattling, nor the Nazis or Imperial Japan who could be bombed and burned and shot into submission. It's a new, persistent threat that our aging leaders are trying to counter with strategies from a different era.
Europe and the US are starting to experience a state of affairs that is already quite familiar to states with weaker central governments. Take your average poor or moderately developed country and the power of the government doesn't extend much beyond the borders of major urban areas. With rural areas not under effective control, the urban population gets used to living with endless, percolating insurgency in The Countryside. And every once in a while a car bomb explodes or a mortar shell lands in the suburbs or someone wearing a vest of cheap plastic explosives blows himself up in a market. That's just life.
This is what happens now. Get used to it. Anyone who claims to know how to stop it either doesn't understand the nature of the threat or is lying.