Nonexperts should be very cautious in offering assessments of airport security measures, or any complex policy issue. There is too much that we don’t understand. Thus, the following is at best a tentative analysis. That said, I suspect that many of the measures the TSA plans to take in reaction to the latest foiled terrorist plot are likely to be either ineffective or not worth their cost. There are three reasons for that suspicion.

First, as I pointed out in this post, many of the TSA’s most intrusive and annoying policies are not used by Israeli airport security, generally considered to be the best in the world; these include forcing people to take off their shoes and confiscating all liquids other than those in special containers. Interestingly, the measures used by the TSA, but not by the Israelis, tend to be highly visible and intrusive to the average traveler. That leads me to suspect that the TSA has adopted them for “security theater” reasons, so as to make it seem that they are making a great effort to combat terrorism, and make people feel more secure. If the public sees the TSA making a major visible effort, fear will perhaps decrease and the agency is less likely to be blamed for any security failures that may occur in the future. Thus, the agency engages in “political theater” measures despite the inevitable grumbling by passengers. The Israeli public, by contrast, may demand less in the way of security theater than American voters, because of the nation’s vastly greater experience in dealing with terrorist attacks.

Of course it’s possible that the TSA experts simply know better than the Israelis. Israeli security experts are far from infallible and they surely make mistakes. On the other hand, Israel has not had a single successful terrorist attack on one of its airliners in decades, and it’s not because the terrorists weren’t trying. So, on balance, I suspect that the Israelis are more likely to know what they are doing than the TSA.

Second, a large, generally free society offers an almost endless variety of good targets for terrorists. It is impossible to secure them all, or even come close. That makes it counterproductive for us to spend large amounts of effort and resources to secure any one particular target. Even if we make planes 100% secure, the terrorists can simply target trains, buses, tourist sites, football games, universities, and other locations where there are lots of people in one place and relatively modest security measures. Indeed, virtually all of the above types of targets have been attacked by terrorists in Europe, Israel, and elsewhere. It makes sense to secure a small number of high-value targets that really are of much greater importance than any other sites the terrorists can attack (e.g. – the White House, the Capitol, nuclear power plants, etc.). But we should not expend enormous resources or impose great inconvenience on people to better protect targets for which the terrorists can easily find alternatives that are almost equally attractive. That doesn’t mean that we should have no airplane security measures at all. But it does suggest that we should be very conservative about deciding what tactics to adopt, and be extremely skeptical of those that are highly intrusive, annoying, or costly.

Finally, the TSA’s new security measures since 2001 often have the air of “fighting the last war.” The 9/11 hijackers used knives and boxcutters to take over planes; so the TSA bans knives and box cutters. Richard Reid tried to put a bomb in his shoes, so now we must take off our shoes. And so on. Terrorists who are at all intelligent are likely to use new methods of attack that we don’t expect. Co-blogger Orin Kerr suggests that the TSA believes terrorists “will want to do the same thing over and over again if we let them.” Orin correctly points out that al Qaeda attacked the World Trade Center a second time after the failed effort of 1993. But it’s worth nothing that they used a completely different method the second time around, one that we were not prepared for, despite (or perhaps even because of) the fact that precautions had been taken against a repeat of the 1993 attack. Nonetheless, it’s certainly possible that the terrorists will repeat effective tactics that worked well the first time. However, the last several attempted attacks (such as Reid’s and the one that just failed) don’t seem to have been well planned, and of course they failed despite the advantage of surprise. If anything, we should want the terrorists to try these dubious methods again, rather than giving them additional incentives to think of new and potentially better ones. On these issues as well, the Israelis have a very different approach that we might be able to learn from, though we probably should not copy every aspect of their system.

Ultimately, I lack the security expertise and access to intelligence information necessary to make specific recommendations on airport security policy. However, I hope that we keep the above three points in mind as we consider how to respond to the latest foiled attack.