1. there is no such thing as "The Ukraine" anymore, only Ukraine, as in the independent country with internationally recognized borders [including Crimea]

2. given russia's long history of dishonesty in their claims (e.g. 'we won't attack Ukraine, that's just western propaganda', 'we are the victims and not the aggressors', 'we aren't raping children in Ukraine'), the truth is, by default, most likely to be the opposite of what russia says (but of course, subject to dispute if russia actually has reliable verified evidence of their claims)

again, it's simply the bayesian prior at this point; the null hypothesis