That is precisely what caused the war: -The Ukraine thought that it was not a threat to -Russia by joining NATO (and later hosting NATO WMD aimed at Russia) -Russia thought that the Ukraine joining NATO was a security threat to Russia.
Hence the war.
The treatment of Russian speaking Ukrainians in Donbas was a secondary matter, IMO. But of course once the war began the spin/propaganda started on both sides.
Just imagine if PNG joined the SCO with the intention of hosting Chinese WMDs aimed at Aus population centres, what would our Pollies & armed forces do? IMO they would be in PNG executing a regime change....pronto .