Your arguments are false and you have been misled or are purposefully misleading!
 Russia was allowed troops at the leased military bases of Sevastopol--but not to prance around with weapons in the rest of Crimea without permission.--But it was Ukraine(and certainly at a time of great weakness)-that opted to refrain from violence hoping that the attack would be reversed by diplomacy(especially under the Budapest Memorandum) not the gun toting Russian commandos who were prepared to shoot had there been resistance that prevented the violence!.-Putin had admitted to planning such a takeover for years( especially after learning of the vast gas reserves discovered in Crimea and Donbas on 2013. Putin's puppet Yanukovych had facilitated such a takeover by placing Russians from Moscovy into high ranking positions to prepare the takeover . The officer ranks were scouted out beforehand and compromised-- it was more threats to family and relatives than bribes that made the biggest difference.