Oh? Never heard of the IRA? or die Luftwaffe? I think they did, in fact, bomb London and brought massive buildings to the ground. And in return the RAF and its allies bombed Berlin with similar results. Japan bombed Pearl, and in return Tokyo and later Hiroshima were bombed. I think quite a few massive buildings were brought to the ground.

The WTC was nearly brought to the ground 8 years earlier when a truck exploded in its parking garage placed there by a fellow named Mohammed Salameh.

The events leading to the creation of the TSA put us on alert, even while the forth airliner was en route to Washington, the plot was foiled. Even without the TSA/DHS, as the passengers, once informed, thwarted the fourth airplane, having heard the news while still enroute. And this was after the cockpit had been commandeered. This cannot happen now due to reinforced doors. Passengers now know a hijack is not a friendly side trip to Havana, these days, but a death threat and will respond accordingly. This was not the case before.

Should we make it more difficult to attempt a hijack? Yup. Will we ever be completely "safe?" Nope. Is the TSA doing this? Well, I'll let them and their track record speak for itself.