We are now hearing rumblings that Russia may be putting a nuclear missile installation in Belarus, specifically, the mobile strategic missile the Topol, though it’s unclear from the report as to whether it is the RT-2PM Topol (SS-25 Sickle), or the more advanced RT-2UTTH (SS-27 Sickle B).
In either case, I’m not sure whether this intended to make the strategic missiles targeting the US less vulnerable to the interceptors, or to imply that these could be launched on a depressed trajectory against the European BMD sites, though I would lean toward the latter.
Belarus borders Poland, and so I would think that interception of missiles launched toward the US would be relatively straightforward, though the kinematics of the missiles in question and the intercept solutions are above my pay grade.
Also, we have reports that the Russian military is looking at commissioning 70 new nuclear missiles over the next 3 years, though reports of a failure in the most recent test of the Bulava SLBM (see also here) might throw a monkey wrench into what seems to be a very aggressive timetable.