It started with a huge LIE. In 1990, U.S. Secretary of State Baker made a commitment to president of the Soviet Union Mikhail Gorbachev that if he retired the Russian troops from Europe, "NATO would not expand “one inch” further East, not even into the former German Democratic Republic."
Gorbachev believed him and indeed retired 380,000 troops from Europe, and of course as soon as that happened, the sly USNATO broke their promise as fast as they could.
From now on, the only goal of NATO was to push eastward , right into Russia's ribs. For that they have used every paramilitary fascist, neo-nazi, or far-right nationalistic groups to break the slavic countries, traditionally and historically attached to Russia.
From the Ustashe in Croatia and Bosnia, the nationalist thugs in Serbia, and now the neo-nazi party svoboda and the nationalistic russophobic group Privy Sektor in Ukraine, NATO has broken Russia's natural allies.
The reason why US/NATO ar so interested in Crimea is that the Maidan's unlegitimate "president and prime minister" in Kiev, promised them to denounce the treaty with Russia concerning the Black Sea navy bases and to expel Russia from Crimea, and NATO install themselves there. With a new base in Crimea and Turkey, NATO would have controlled the Black Sea AND the Meditterranian Sea. In their wake the Soros-kind of sharks would appropriate for big money companies the wealth hidden in the Black Sea bottom ...
Well, Putin read through them like in an open book, and shattered their plan. Now NATO enrages that they "lost" Crimea, which was never theirs in the first place. That's why Kerry, Biden and Rasmunssen are foaming at the mouth.