New details of the architecture of the Yemen-originated parcel bombs take us deeper into the minds behind the plot.
First, that they remain driven by one apocalyptic scenario: blowing up a plane over a major U.S. city.
Second, the routes they have chosen reveal the bombers' own sense of their technical limitations as well as their way around these limitations.
In the case of the Christmas underpants bomber and the latest plot, the target was the great urban sprawl along the Great Lakes: Cleveland, Detroit, and Chicago. It doesn't require pinpoint accuracy to hit densely populated areas there. A plane on approach to any one of those cities will be over populated areas for an hour or more, giving plenty of leeway for a timed explosion. (As opposed to the Northeast, where Boston, New York, and Washington are far more concentrated with large rural expanses between them.)
Third, the bombers have deployed easily accessed open navigation systems: In the first case, the underpants bomber timed his attempt by following the onboard moving map, in the second the plot has involved the parcel carriers' very accurate and efficient tracking systems. As ABC News first disclosed Monday, a dummy run using parcels mailed from Yemen was made in September, and intelligence officials intercepted them, an early hint of the new techniques.
We now know that both of the so-called printer bombs employed circuit boards from cellphones to activate the detonators. There were no SIM cards, so that they could not be triggered by a phone call. They were designed to act as timers.
Having failed with two attempts using open navigation systems, what will they try next? It's a question that requires intelligence techies to think like the alleged master bomber, Ibrahim Hasan al-Asiri.
And remember that behind all this calculation lies the understanding of the global media impact of a plane turned into a bomb raining death from the sky, the ultimate purpose of the terrorists.