You can be sure that the perpetrators of this act will be hunted down and dealt with in some way. A few hundred people can apparently be overlooked to some extent, but thousands of people, as well as the total destruction of the world's economic nerve center, will absolutely prompt some kind of response that's going to involve more dead people. With any luck it will be done delicately enough "through channels", as Sean suggests. Now they are talking to Pakistan, which is a nuclear power. I am still not up for World War III.