The Islamic fantasist now thankfully shot dead by Australian police is from the same mould as the two African Muslim nut jobs who killed Drummer Lee Rigby. They had a history of public frustration, run-ins with the police, mostly as a result of delusions of worth; they thought they were special, the societies about them didn't accord them the status they imagined they deserved, and eventually they caused the death of others. I'm sure every police force in the UK has a list of this type of Muslim nutter. They push the boundaries as far as possible - ranting at beat coppers, sending offensive letters or being prats on Twitter - and of course make no secret of who they are or their perverse, deviant world views. They are a breed of threat, in other words, in clear sight - and now they are being encouraged to rise up and slaughter the Kaffir (that's us).
They should not be confused with 'professional' terrorists, who make every effort to be invisible, not to stand out, to hide in the anonymity of mass populations. The Jihadi nutter is exactly that - more likely than not to be suffering from a mental disorder, commonly delusional fantasists. Which doesn't mean they can't use a gun or edged weapon to cause havoc. And unless we introduce internment - and our experience from Operation Demetrius in Northern Ireland from 1971 - 1974 has demonstrated how pointless and counter-productive that was - we must wait until they act before taking them down.
And yes, taking them down is about the only logical and sensible way of dealing with them. They must be shot down like mad dogs. There is no defence against such people - we will have to accept a low level of attritional casualties until they expose themselves and can be lawfully culled.