On Saturday March 1, 2014. According to Putin request Russian upper parliament approved deployment of Russian troops in Ukraine.
This is a direct violation of Budapest Memorandum. It states that the aforementioned countries will: "...respect the Independence and Sovereignty and the existing borders of Ukraine." and "... refrain from the threat or use of force against the territorial integrity or political independence of Ukraine, and that none of their weapons will ever be used against Ukraine except in self-defense..."
Yesterday, on March 1, 2014, Russian troops took under their control two airports in Crimea. And brought ~700 solders. It was just probing of reaction of the West. West did not react strong.
West should strike with political sanctions. And strong counter-aggression