This is an under-appreciated point. We've forgotten all the old hard Cold War lessons about escalation.

What we are seeing now is a huge expansion of deniable and proxy warfare. Everyone is still (I hope) clear that sending an actual tank division across the Polish/Ukraine border would be met with nukes. So the question is, what is the largest most damaging attack that can be carried out without reprisal, and how do the participants find this out?

And of course, the ultimate in deniable attacks is one carried out by the enemy's own forces. Did cyberwarfare crash a US destroyer into a cargo ship? (Almost certainly not, but maybe next time). SWAT-ing is already established as a tactic; could suitably forged communications or "fake news" disseminated via the President lead to the SWAT-ing of a country? There are some suggestions that this applies to the Qatar situation.

> Everyone is still (I hope) clear that sending an actual tank division across the Polish/Ukraine border would be met with nukes.

Only if those tanks are under foreign flags. If they're under "rebel" flags, then nobody cares.

> SWAT-ing of a country

Iraq comes to mind, although the forged information came from the invading country's own services.

That should come as a hint that state actors are not the only ones capable of deploying informational weapons.

I think Ahmed Chalabi played a key role there as well, and there are suggestions that he was an Iranian agent.

There's no denying that Ahmed Chalabi was an Iranian agent of influence, but whether he was working for the Iranian clandestine services is unknown.

Do these missiles require a working communications network? If this goes on long enough, there might not be any way to launch them.

I know not with what weapons the first world cyberwar will be fought, but I know the second will be fought with floppy disks.

Why do you think that different countries have put missiles in submarines ?

And Russia reportedly even has a deadmans-switch that can be triggered by seismic activity on Russian soil and rapid changes in air pressure. I'd presume that such a system is not connected to the internet.

All of those systems predate the Internet, so you bet nuclear capabilities will not be affected much by cyber attacks.

Nuclear capabilities will probably not be affected much by cyber attacks over the internet. There are other vectors, but they obviously require a much more serious investment in espionage, spycraft, etc.

Isn't this literally the denoument of Dr Strangelove?