http://theconversation.i2p/russias-long-journey-from-partner-of-the-west-to-pariah-reflects-a-huge-failure-of-its-diplomacy-182008
From what Putin and his foreign minister, Sergei Lavrov, have said in the run-up to, and since, February 24, when Russian troops crossed into Ukraine, it is this fear and resentment of an isolated Russia surrounded by pro-EU and Nato countries, that has led to the current conflict.