It's great that Amsterdam's airport has announced it will body scan all passengers bound for the US, and Chicago is adding more units, but it'll cost billions to add these high tech machines to every airport security gate from Nantucket to Namibia, and every airport will have to be so equipped, otherwise potential terrorists will find the weakest link in the system and exploit it. There are only 40 scanners in use at US airports currently, with 150 more already purchased but not deployed, and another 300 planned. But with over 2000 security lanes at US airports alone, and thousands more worldwide, that's only a drop in the bucket.

And where will the funds to add thousands more of these scanners come from? Ultimately, from either tax dollars or from an increase in the airport security taxes. Currently, the US charges a 9/11 security fee of $2.50 per segment up to $10 per flight for domestic flights, and foreign governments charge their own additional security fees. You can expect those fees to go up if scanners are added.

And then there are the privacy concerns, with forces on both the right and the left arguing that these full body scanners invade the privacy of passengers, showing as they do the full contours of one's body. Will little children be forced to go through them? If not, will some extremist tape explosives to a child and put him on a plane?  On the plus side, newer versions of body scanners are designed to effectively catch hidden items while not showing as much of the human form.

And besides the cost, will these scanners be totally effective? We've read that explosive material inserted into a body cavity could escape detection, much as contraband cocaine does when swallowed in little plastic bags.

And all this doesn't even address the issue of explosives in cargo or checked luggage.

Our best protection, which will never be 100% failsafe, is to concentrate on intelligence, but in the most recent terrorist attempt, intelligence turned out to be woefully inadequate. I won't go into all the failures, since they've been covered extensively elsewhere, although I have to ask what would have made airport security and our intelligence services take Umar Farouk Abdulmutallab seriously. Carrying just a backback on a long haul flight, paid with cash, on the National Counterterrorism Center's database of known or suspected international terrorists, UK visa revoked....would he have had to carry an AK-47 to get noticed?