The second reason, however, is non-military and preventive. Firstly, this decision must tie Belarus even more strongly to Russia. Deploying nuclear weapons certainly is because it is also «legitimate to protect» these weapons. Not that Moscow does not apply this principle to its forces today, but nuclear weapons are still a degree stronger. Secondly, deter NATO and the European Union, but not in a military sense.
If there should be unrest in Belarus again, Russia has something to prevent the secession of Belarus. There have been very large anti-Lukashenko riots in Belarus, the suppression of which the West «expressed concern». This move allows Moscow to intervene much more even after Lukashenko. A tactical nuclear weapon must ensure that the collective West «pulls back several degrees» in support of democratic aspirations. No one wants instability in a country that has nuclear weapons and does not even belong to that country. Russia wants to preserve its «rights» to Belarus after Lukashenko.
In fact, we do not know if any nuclear weapons will be deployed in Belarus at all. The US has expressed concern, however, has consistently stated that there does not appear to be any unusual activity with nuclear weapons. The NATO Secretary General also announced that he does not consider it necessary to revise the defense plans, because the situation has not changed significantly.
All in all, it is a rhetorical move aimed at dragging another occupation net over Belarus. The announcement of the placement of a tactical nuclear weapon is aimed at influencing the West and controlling Belarus after Lukashenko. Its activities have no military effect.