Do you think there will be another terrorist attack in the US that's worse than the 9/11 attack?

I suppose there will be another one terrorist attack in the US. Of course that sounds horrible. I believe that it will not happend. But the US is quite attractive for terrorists due to its power and impact.

No-one can predict what will happen
in the future.
The U.S.A has very tight security so its not
probable.
Who knows what tommorrow will bring ??