Banning box cutters since 9/11, or taking off our shoes since Richard Reid, has not made us any safer. And a long-term prohibition against liquid carry-on items won't make us safer, either. It's not just that there are ways around the rules, it's that focusing on tactics is a losing proposition.

It's easy to defend against what terrorists planned last time, but it's shortsighted. If we spend billions fielding liquid-analysis machines in airports and the terrorists use solid explosives, we've wasted our money. If they target shopping malls, we've wasted our money. Focusing on tactics simply forces the terrorists to make a minor modification in their plans. There are too many targets -- stadiums, schools, theaters, churches, the long line of densely packed people in front of airport security -- and too many ways to kill people.

Security measures that attempt to guess correctly don't work, because invariably we will guess wrong. It's not security, it's security theater: measures designed to make us feel safer but not actually safer.

Airport security is the last line of defense, and not a very good one at that. Sure, it'll catch the sloppy and the stupid -- and that's a good enough reason not to do away with it entirely -- but it won't catch a well-planned plot. We can't keep weapons out of prisons; we can't possibly keep them off airplanes.

The goal of a terrorist is to cause terror. Last week's arrests demonstrate how real security doesn't focus on possible terrorist tactics, but on the terrorists themselves. It's a victory for intelligence and investigation, and a dramatic demonstration of how investments in these areas pay off.

And what can you do to help? Don't be terrorized. They terrorize more of us if they kill some of us, but the dead are beside the point. If we give in to fear, the terrorists achieve their goal even if they are arrested. If we refuse to be terrorized, then they lose -- even if their attacks succeed.