Terrorism existed before 9/11, an interesting read from a pilot about the current state of security theatre at airports. Read the first few paragraphs and try to imagine that happening today and what the reaction would be.
In the 1980s we did not overreact. We did not stage ill-fated invasions of distant countries. People did not cease traveling and the airline industry did not fall into chaos. We were lazy in enacting better security, perhaps, but as a country our psychological reaction, much to our credit, was calm, measured and not yet self-defeating.
You might also consider the illustrious words of Philosoraptor regarding terrorism and security.