If you wage war on foreign nations, and allow your government to do so, then you shouldn't be so surprised when it comes back to roost. No, the WTC attacks were not justified. But they were definitely to be expected, given the carnage around the world that the USA has been propagating now, for 80 years. When your nation maintains its moral authority to indiscriminately wage war around the world, you should not be surprised when that war comes to your footstep.