Ukraine: What's Going On?

Could someone explain why we are getting involved in this latest "crisis" between Russia and the Ukraine?  Are we insisting that democracy be imposed on every nation and that every people must have elected officials that we approve? It's a noble thought. But extremely naive and impractical in some countries. I think we need to step back and let some countries solve their own problems and not make those problems ours. Don't we have a plethora of problems in our own country that need attention ?