(Spencer Platt/Getty Images)
While security around New York City's metro and rail stations may have improved, there are countless vulnerabilities. Indeed, "all the security measures in the world which are centered inside of New York City are likely to be of little value if they are not mirrored throughout any rail system that runs into the city. If I am a terrorist and I want to detonate explosive devices on trains running into New York City during the morning rush hour, I am not going to carry those bombs into Manhattan by car or foot and then try to board a train in the teeth of security," Faddis writes. "This gets to a fundamental law of counterterrorism: Terrorists do not stage frontal assaults on your more defensible front. They feel along your perimeter until they discover what you have missed, and then they strike where you are weak."
Examples: In 2004, 10 bombs exploded in Madrid on trains traveling from the suburbs into the city. 191 people died and 1,500 were wounded. A year later, three subway trains in London were bombed killing 56 and wounding 700. One year after that, bombs on the Mumbai subway killed 200 and wounded 700. On March 29, 2010 a double suicide bombing in Moscow's subway system left 39 dead.
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