The Nice attack appears to be the most chillingly perfect demonstration yet of how devastating low-tech terrorism can be - and one that has particular ramifications for Australia.

After the Paris and Brussels attacks, Australian authorities delivered the reassuring message that three key differences distinguished our own threat situation. Our extremist networks, while serious and enduring, are relatively small compared with Europe's; our island nation status gives us a strong advantage in controlling movement across our borders; and our strict gun laws make it very hard to get hold of powerful firearms.

The final of these strengths is a critical defence that keeps Australians safer and is consistently highlighted by national security officials. But it doesn't apply when an attacker can drive a large lorry into a packed crowd. Vehicles have formed part of attacks or plots before, but usually as enablers - running down a police officer and taking his gun to then use on others for instance.