Modern ICBMs have to deal with anti-missile defense systems. A common way to counter missile defense is to overwhelm the system with multiple targets. You only need one warhead to get through, after all.
Enter the "Multiple Independently targetable Re-entry Vehicle" (MIRV). Basically, rather than having a single guidance system / warhead, you have several, which separate from the initial launch vehicle and operate independently.
In normal spaceflight terms, you could think of it as a first stage that puts the ICBM roughly over the target, and then the second stage breaks into a dozen pieces to increase survivability. So theoretically, that first stage could be recovered and reused.
Is it Worthwhile?
Re-use would certainly add costs - R&D, extra weight in fuel, control surfaces, etc.
It could also save costs - the US does test launches from time to time, in part to test the systems, and in part to remind everyone that the capability exists.
I question whether we do launches often enough to actually recoup the costs, but I suppose if SpaceX and others "solve" this problem, it might be inexpensive to add the capability on future ICBMs.
Also, you could theoretically deliver conventional munitions from an ICBM with MIRVs, enabling rocket re-use for far more frequent launches, but you run into the issue of "conventional strikes now look like nuclear first strikes, which can be destabilizing."