AP Photo

More than nine years into our struggle against catastrophic terrorism, we still don't know how to find the needles in the civil aviation haystack.

Aviation security has bedeviled us since 2001, in part because we have reacted to past incidents instead of planning strategically for the future. After 9/11 we banned box cutters, scissors and nail clippers; after Richard Reed we started X-raying shoes; after the 2006 London airliner plot we banned liquids over 3 ounces. And now, after a would-be bomber last Christmas hid explosives in his underwear, we are starting to peer beneath passengers' clothes with scanners.