Soldato
You think invasions are decided based on official language rules? Don't be silly.
The trigger of the invasion was Yanukovych losing power. Russia started the "military exercies" one or two days later.
Nope.
I think that the current interim government alienated the ethnic Russians in the autonomous republic of Crimea, and elsewhere in Ukraine.
The fact is, the government of the autonomous republic of Crimea requested Russian support.