I've said this from the beginning and made the apt comparison to USSR putting nuclear missiles in Cuba.
http://www.zerohedge.com/geopolitical/dozens-wikileaks-cables-show-us-knew-nato-expansion-was-russias-bright-red-line
FWIW, I'm persisting with my view that Ukraine was/is the start of WW3, and this US aggression, and particularly the USD weaponization, will be, from an historical perspective, the straw that broke the US-Empire-camel's back.