Interesting that you should say that ICBMs cant be used for tactical strikes, perhaps that is the case, however the US and UK have moved to arm their SLBMs with lower yield warheads for precisely the use in tactical strikes where the higher hundreds of kiloton warheads would be overkill. If you envisage a "demonstration of intent" type strike, like retaliating against a North Korean attack on Seoul with nuclear weapons say, then a SLBM or ICBM is possible, infact potentially preferable to a nuclear cruise missile. Perhaps time a time sensitive leadership target that requires a prompt nuclear response, that would favour a ballistic missile over a cruise missile. on two counts, speed of response and higher chance of penetrating air defences compared to CM. I am aware some peer nations have a ABM capability , but that's a different scenario to the one I outlined. If your talking about a wider theatre nuclear conflict then nuclear ALCMs are useful but they are not great against certain hardened targets, C3M bunkers or missile silos for example.