As Ukraine has expressed interest in joining NATO, and Russia has expressed vehemently how against they are about the issue. As the west talks with Ukraine, an unusual amount of Russian troops have moved to the border. Though Russia says that the deployment of these troops are only after Ukraine “deployed half of their army” to Donbass. Dmitry Peskov a kremlin spoke about that if these troops were deployed in the conflict zone (donbass), Russia’s concern would increase ten fold due to the proximity it has to the russian border. Peskov also said that the conflict could be resolved with Russian-backed separatists rather than the military
I believe that yes Russia has the right to be concerned about Ukraine joining NATO (if they do). Though this does not permit the number of troops to be sent to the border. Though you can also see from the Russians side that they were just matching Ukraine, so to speak, with the deployment of troops. Though the number that was given for the deployment of the Ukrainian troops was only an accusation, rather than a fact. This conflict has also been going on for almost a decade which will have the tensions being very high between both countries, so if diplomatic peace cant work it seems that military will prevail.
The Kremlin is working on a realistic theory. The Kremlin seems to be working in the defensive. With Russian power almost being on decline, Moscow has been trying to maintain all of the power that they have, while keeping their citizens safe, by deploying troops to the border it would be doing both of these. NATO is a working IGO. Collective security could be applied as well with Ukraine wanting to join NATO to gain security from Russia, and NATO could gain power with the induction of Ukraine into NATO due to the proximity to Russia. Ukraine is partaking in the security dilemma by adding troops to the area causing a reaction by Russia.