Bear in mind ‘we’ likely know how to shut down the Iranian grid, the Iranian internet, the Iranian PSTN and Cell networks and their RF comms.
All modern societies, even second and third world countries, rely on the above.
It’s a new sort of MAD - in cyberwarfare.
It would take months and perhaps years to recover from the damage done by such a cyberattack.
We however could respond in more conventional ways against their infrastructure, from which they could not likely recover in less than a century.
It’s called Asymmetrical Warfare.