As far as war crimes are concerned, the only evidence I have seen of crimes shows Ukrainians torturing and killing Russian POWs. If you have actual proof of Russian crimes, please share a link. Thanks.

Also, here is a cable from William Burns explaining the Russian position

https://wikispooks.com/wiki/Document%3ANyet_means_Nyet;

"Russian Opposition Neuralgic and Concrete

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5. (C) Ukraine and Georgia's NATO aspirations not only touch

a raw nerve in Russia, they engender serious concerns about

the consequences for stability in the region. Not only does

Russia perceive encirclement, and efforts to undermine

Russia's influence in the region, but it also fears

unpredictable and uncontrolled consequences which would

seriously affect Russian security interests. Experts tell us

that Russia is particularly worried that the strong divisions

in Ukraine over NATO membership, with much of the

ethnic-Russian community against membership, could lead to a

major split, involving violence or at worst, civil war. In

that eventuality, Russia would have to decide whether to

intervene; a decision Russia does not want to have to face."