Aside from the numbers game, ICBMs used to be the fastest way to deliver a warhead, with the obvious drawback that anyone watching the horizon can see it coming from half a world away.
Nuclear warheads have been further miniaturized since the cold war, it is now possible to fit them into cruise missiles.
> The deployment of Kalibr missiles, long-range, low-flying, capable of carrying conventional or nuclear warheads, available in land-attack, anti-ship and anti-submarine variants, was said to have altered the military balance in Europe and potentially compromised the NATO missile defence system under construction in Europe. [0]
There's also the rumored/propagandized hypersonic, nuclear powered cruise missiles (skyfall [1]) that are meant to defeat missile defense and circumvent MAD by enabling undetected first strike.
Nuclear warheads have been further miniaturized since the cold war, it is now possible to fit them into cruise missiles.
> The deployment of Kalibr missiles, long-range, low-flying, capable of carrying conventional or nuclear warheads, available in land-attack, anti-ship and anti-submarine variants, was said to have altered the military balance in Europe and potentially compromised the NATO missile defence system under construction in Europe. [0]
There's also the rumored/propagandized hypersonic, nuclear powered cruise missiles (skyfall [1]) that are meant to defeat missile defense and circumvent MAD by enabling undetected first strike.
[0] https://en.m.wikipedia.org/wiki/Submarine-launched_cruise_mi...
[1] https://en.m.wikipedia.org/wiki/9M730_Burevestnik
Disclaimer, I'm just a web developer with access to wikipedia yo