Government orders the major internet service providers to shut down their services, presumably :) Not saying that that would necessarily be easily to coordinate, nor that the loss of internet wouldn't cripple the global economy. Just that it seems to be a different order of risk than an extinction event.

My intuition on the matter was that an AI would be limited in its scope of influence to digital networks, and its access to physical resources, e.g. labs, factories and the like would be contingent on persuading people to do things for it. But everyone here is so confident that FAI --> doom that I was wondering if there was some obvious and likely successful method of seizing control of physical resources that everyone else already knew and I had missed.