As usual, western propaganda at its best... the western media tells its audience about all these new Russian weapons, but it fails to tell the full story as usual.
The reality is that the new arms treaties which Russia and the US have signed has reduced dramatically the number of warheads each side can have and no arms race is actually possible without breaking that agreement and there is
no evidence either side has broken it yet.
The Russians are developing new weapons because their old weapons were Soviet and they don't want to have to share secrets with countries that now seem to want to enter NATO or are part of NATO.
The whole concept of nuclear deterrance is based on mutually assured destruction... if one side has an enormous anti missile infrastructure along with a reduced number of nuclear weapons for both sides and a powerful conventional capability and a military alliance that includes most of Russias European neighbours then this undermines the nuclear deterrent. A powerful strike against Russias nuclear facilities... which are limited by treaty in location and number, might lead to a situation where they might decide they have enough of a missile shield to stop anything they don't get in the first strike attack on Russias nuclear weapons assets. In other words an ABM system actually makes nuclear war more likely... rather than less likely.
The irony is that the military industrial complex that builds the ABM system will make all sorts of promises as to its effectiveness and it might just take one president to believe them to start a war that no one could win. For Russia the thought that their missiles do get through and wipe out the US will be of little compensation.
The ABM systems now are unregulated and destabilising and so the Russian solution of rail mounted missiles makes an enormous amount of sense. Currently truck mounted missiles are limited to deployment areas by treaty, but rail mounted missiles can be rapidly dispersed in hours over an enormous area amongst millions of other very similar looking carriages... it is a perfectly natural solution to the problem posed by the US ABM system.
The destabilising nature of ABMs is why they had an ABM treaty in the first place.