The threats were always there, we only got aware of them since 9-11 and 4-11.
It wouldn't surprise me though if there are going to be more terroristic attacks this summer. If you consider the mess in Iraq and the even bigger mess in Israel that are being made by, or with the help of the US.
It is time that the US starts to clean up the mess it made in the past instead of creating an even bigger mess to camouflage the old mess.
Untill that has happened there will always be a serious threat from terrorism.