It appears according to Putin that NATO expansion is the cause of Russia invading Ukraine.
An agreement about NATO expansion apparently had been made in 1990, this being that NATO would not expand beyond the reunified Germany.
After this agreement, in 1992, Russia aided in the 'liberation' of Transnistria from Moldova as well as Abkhazia and South Ossetia from Georgia. Both areas had a substantial Russian population which some would argue was the reason for Russian intervention. Since then, Russia has helped to 'liberate' Crimea from Ukraine, an area of Ukraine with a large Russian speaking population. Following this, other areas of Eastern Ukraine sought independence, which is when the frozen conflict started which resumed in 2022.
Nations on the borders of Russia, watching how Russia had helped with the liberation of parts of Moldova and Georgia understandably became concerned that they would be next. So when someone blames NATO for its expansion, ask them if those new nations should have trusted a nation which invaded, and still occupies, old parts of the USSR to create a Greater Russia.
And if people feel that Russia has a right to obtain its ancestral lands, does China have that right with territory that now belongs to Russia?