Further, the next generation of terrorists will grow up in a digital world, with ever more powerful and easy-to-use hacking tools at their disposal.
While the vast majority of hackers may be disinclined towards violence, it would only take a few to turn cyber terrorism into reality.
While many hackers have the knowledge, skills, and tools to attack computer systems, they generally lack the motivation to cause violence or severe economic or social harm.
The concern is over what will happen as strong encryption becomes commonplace with all digital communications and stored data. Right now the use of encryption isn't all that widespread, but that state of affairs is expected to change rapidly.
If we take as given that critical infrastructures are vulnerable to a cyber terrorist attack, then the question becomes whether there are actors with the capability and motivation to carry out such an operation.