Knowing you have a stealth ICBM doesn't change a thing if there is no way for the other side to defend against the non-stealth ones, so it wouldn't be a deterrent to most possible adversaries, but the optics of disclosing such a thing developed in, say, the 90s wouldn't be great.

Those that might conceivably try to defend themselves against conventional ICBMs are few and might very well know such a thing exists, it may work as a deterrent in that context.

If such a thing exists at all, not quite sure how you might make an ICBM stealthy, couldn't think of a way to hide launch and reentry signatures...

Having just any weapon is worth keeping a secret. From the moment you have a weapon, and an enemy, the later will try to disarm you.

Not 'worth keeping a secret' - worth controlling the information revealed about it. In the case of nuclear weapons, you want to keep its weaknesses and fallibilities secret while trumpeting its existence from the rooftops. The more parties know you have a mega-weapon, the lower the chance you'll have to use it.

> The more parties know you have a mega-weapon, the lower the chance you'll have to use it.

But if you have to... the lower you have a chance to win, as the enemy with more than 1 gram of gray matter will do just anything to take it down before you can shoot.

Betting all of your strategy on assumption that the enemy is scared enough of you not to attack is stupidity beyond all bounds.

If you attack someone, especially if you attack somebody stronger than you, then you attack with all force available to you, and maximum ferocity.

You assume the enemy will willingly throw away his biggest chance to take away your biggest force multiplier, and the biggest chance to win?

> If you attack someone, especially if you attack somebody stronger than you, then you attack with all force available to you, and maximum ferocity.

True, IF you attack someone. But if you see someone who is unassailably stronger than you, that you couldn't possibly defeat, then you don't even go there. And that is the point of MAD. An enemy with one nuke is scary, scary enough to make them worth attacking. But an enemy with thousands of nukes, scattered across the globe, in unknown locations, which will launch at their signal (or lack of signal)... You just don't attack them.

And that's an extremely dangerous assumption. You don't need to dive deep into history for good examples of the opposite.

And if you dive deeper, you will find examples far more suicidal disparities in between warring factions.

Second, you do not count in a possibility of your opponent not even trying to win. If wars were fought by rational people, we would've long had math PhDs for generals.