How do you practice finding terrorists?

Some time ago in an American airport a man came up to the man in front of me in a line. He had a packet of white powder in his hand. He showed the man in front of me a very official looking badge (although he wasn’t in uniform or anything) and asked the man to put the bag of white powder in his backpack. This was a test for the sniffer dogs in the next area. The man wasn’t to do anything special. Just behave normally.

In the next area the most darling little beagle,¹ in uniform, came sniffing along the line, with a different man in uniform on the end of its lead. I was excited. When the beagle got to the man in front of me, who had put his backpack on the floor, as many of us had, the beagle took a sniff or two, sat down promptly and looked pretty intently at his handler. I was watching pretty intently myself, and I hope the beagle ignored me. The handler, all serious like, asked the man if he could please open the backpack. The man complied. The handler found the bag of white powder, took it and gave it to the beagle, who gave every sign of being very, very happy. Then the handler took the bag, praised the beagle, gave him a rub, and the two of them ran off playfully and joyfully behind some screens.

Score one to the ever vigilant forces of law and order.

I mention this because of an extremely interesting article about security at Israeli airports. It isn’t a new article. It has probably been resurrected in response to various anguished goings on to do with heightened crotchal area search opportunities.

The main point of the article is that Israeli security agents are not looking for bombs, or explosives (or drugs?). They’re looking for terrorists. They are interested in how you react to their mostly innocuous questions. And by all accounts they are very, very good at what they do. So here’s my question:

How do you practice finding terrorists?

You can’t go up to some bloke on the way to the airport and ask him to smuggle a bomb onto the plane. That behaviour is surely not going to be the same as a genuine terrorist’s. There are reams of scientific papers on the fundamentals of this sort of task, where positives are rare, and the penalties for missing them high. How often to slip a test through, how long to work a shift, how to reward detection, how to foster decision making, balancing reliability and accuracy, and all that. I am sure that even dumb airport security theatre follows most of those guidelines much of the time.² But it must depend on testing the system from time to time. I see how you do that with a pretend bomb, or even a real bomb. I don’t see how you do it properly with a pretend terrorist or even a real terrorist.

Unless, maybe, you have such good intelligence that you almost always know when something is going down, don’t tip the hand of your normal security, and stand by to do the needful at the last possible moment.

Which is kind of what the article hints at.