Few events are so horrific that they can’t be believed. The attacks Sept. 11, on the World Trade Center and the Pentagon are just that. At this writing, the death toll isn’t known but could approach 6,500. It is the worst bloodletting on U.S. soil since the Civil War.

To me, the idea that the twin towers of the World Trade Center no longer exist is hard to fathom. When I worked in New York City in the early 1990s, I used to climb up on the roof of my Brooklyn apartment on pleasant nights just to view the tall majesty of the Trade Center. In 1993, I climbed up once again after the first terrorist bombing there. My wife and I saw helicopters pluck survivors off the top of the towers. But the towers gone? Unthinkable.

Amid all of the shock and anger, a few ideas come to mind. One is that it is a tremendous thing to see Americans pull together. Another is that Americans need to realize that we have enemies who can do tremendous damage on our own land. The U.S. was lulled into a false sense of security after the end of the Cold War. In the late 1950s and early 1960s, by contrast, I remember crawling under my school desk as klaxon horns wailed. We were waiting for Soviet nuclear weapons that luckily never came. Until Sept. 11, those air raid drills seemed like a distant, if not quaint, memory.

As I consider my own sense of shock and anger, however, I am stunned by something else. I can understand that tiny groups of suicidal fanatics can do so much damage. Yet, what seems incredulous is how the terrorists were able to do it. Instead of spending billions of rubles putting together nuclear bombs as the Soviets did, they pulled off this horrible tragedy on the cheap. Playing on American complacency and self-absorption, they managed to turn ordinary jet airliners into incredibly lethal weapons. Even more remarkable, 19 terrorists managed to penetrate airline security and hijack four aircraft within a few hours of each other. One location was Dulles International right here in Virginia.

Four planes? Where were American and United Airlines, who shared responsible for security? There have been warnings galore of potential terrorist attacks, notably the 2000 Bremer Commission on terrorism. Yet, the Americans were too busy watching golf matches or the fluctuating stock market. Despite years of warnings, airlines didn’t seem to bother much with upgrading security. Instead, they were obsessed with keeping gate times short so they could get more planes in the air, keep the cash flowing and pacify analysts on Wall Street who couldn’t see beyond the next financial quarter. The public has been just as myopic: Self-absorbed passengers howl in outrage at the slightest airport delays or inconvenience.

This will change. Having lived abroad and traveled widely in Europe, the Middle East and Asia, I will always be amazed at how much longer it took to get on aircraft in other countries. You couldn’t just dump your bags curbside and hop on board with an electronic ticket. But then, the countries I was visiting were far more used to terrorism and civil strife. These countries were generally older than the U.S., and now they seem a lot wiser.