Police regularly stage anti-terrorism drills in which dozens of officers from all over the city are directed to converge quickly on a central spot, a practice run to minimize confusion if they need to swarm into an area during a real attack.

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Then again, Groupon has a similar, if less capital-intensive, need to build out a sales force to attack each new local area.

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That whole area is very spread out, so they would need to conduct a massive, co-ordinated attack on several facilities all at the same time and the Saudis seem to be alert to this ambition.

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