But consider the *gotcha* second bomb intended to kill emergency responders and police after a first, diversionary bombing, and recall that plane crash in Queens a few days after the 09/11 attack. And consider that our enemies, foreign are likely more familiar with NY than any other of their favoured targets, and that an attack on NY as a followup to the sort of event you describe would not only guarantee them the publicity they crave from the assembled world's journalists, but would also prove that they can hit *the great satan's* largest city repeatedly, any time they so choose. And with the high concentration of a Jewish population in NY, HAMAS may find such a closely gathered collection of unarmed Jews to be a more inviting target for revenge for the death of one of their own leaders than Jews in Israel who can shoot- and bomb- right back.
There are lots of potential attack tactics, and many potential attackers. And it only takes one successful one to set the example for others to copycat any success, even a limited one.