The problem with biological attacks is that the agent can be designed for years, then spread quickly and the process to stop it after it has been spread is hard

The problem with biological attacks is that the agent can be designed for years, then spread quickly and the process to stop it after it has been spread is hard; the virus/bacteria has to be found, analysed and then some specific solution/treatment must be found/designed. In days or weeks. That is why I selected biological methods as an example. There will of course probably be many other areas where it might be easier to make an attack than to defend against one. My point was -- this discussion will almost certainly get more intense, because of more extreme threats. [In some areas, the technological development will make it harder for the attackers, in others it will be much easier. And attackers choose how they attack.] Edit: Clarity.