An advantage that terrorist organizations such as the IRA and ETA was that they had a single unified purpose a command structure, they new each other, and operated in an environment they felt safest in.
These new leaderless terrorist organizations operating on the fringes have no real command structure for planning and intelligence gathering.
They are capable of one shot operations at most, then they have to go on the run for the rest of there life's.
This is why there has not been the concentrated bombing campaign in Europe and more strikes against America.