[agurk]

Some SLBMs (Submarine Launched Ballistic Missiles) use star sighting to correct their trajectory mid-flight. ICBMs launched from silos know exactly where they're starting from, whereas a submarine is both moving, at different depths and has some error to knowing exactly where it is. Missiles use inertial guidance, so knowing your starting your point is crucial.

How accurate a missile needs to be is a whole other dimension though. If the value of a missile is as retaliation to destroy a city (countervalue) then it can be a large warhead and "miss" by quite a margin but needs some form of credible survivability of an enemy first strike. If the missile is to be used to destroy enemy military installations (counterforce) then it needs to be a lot more accurate but usually the implication is as a first strike so less survivability is required.

When you have nuclear weapons that you can drop from manned aircraft, ICBMs from silos and SLBMs controlled by different military branches there is going to be a lot of politics over what the missile is for, which will determine its required accuracy, which will be a factor on if it needs star sighting.