Not necessarily.
Silo based Missiles usually are Liquid Fuel. And Silo missiles are still used by Russia, China.
The RS-28 Sarmat is brand new and its liquid fueled.
The advantage here in underground silos is that the downside of storing solid fuel is negated, the thing only explodes if the fuels are mixed, so generally liquid is safer underground.
Secondly Liquid Fueled missiles can travel further and carry bigger payloads, compared to solid fueled missiles, and easier to build. They can also regulate thrust better and can shut engines mid flight and then restart again, whereas the Sulid needs to burn throughout usually.
This is why Liquid is preferred if you have silos, b/c the main disadvantage of liquid missiles is the time to set up the launch, but if its in a silo and underground whether you are taking 1 day or 1 hour, they don't know, they can't see underground from satellites. Liquid is preferred for heavy payloads and things where you need range, b/c the liquid fuel is more efficient than solid.
Ideally you would want a balance. you want your Silo missiles to be liquid and heavy and long range. You want your road and even rail mobile missiles to be solid, as they need to be launched quickly before you get bombed at the staging site.
,TB3 fires mini cruise missiles.
