The security checkpoints worked. Because we screen for obvious bombs, Umar Farouk Abdulmutallab -- or, more precisely, whoever built the bomb -- had to construct a far less reliable bomb than he would have otherwise. Instead of using a timer or a plunger or a reliable detonation mechanism, as would any commercial user of PETN, he had to resort to an ad hoc and much more inefficient homebrew mechanism: one involving a syringe and 20 minutes in the lavatory and we don't know exactly what else. And it didn't work."
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