Obama is a liar, So why should any be "baffled" when he does so to make his case against Putin. He sure hasn't corrected past lies with the truth....he won't this either.
The problem everyone has is discovering who is telling it like it is.......and neither Putin nor Obama will do so. Neither will the news sources who all report according to the bias of the networks etc.
This is EU's Problem and interesting that few are calling them to account for their actions, nor the US for theirs in Ukraine.
He is also a liar, when he claims that Crimea independence and its reintegration in the Russian Federation "are breaking the international law". There is no legal reason whatsoever to put sanctions on Russia.
The International Court of Justice, supreme arbiter in matters of international law, in 2010 ruled that the declaration of independence of Kosovo had been legal and also, more generally, that throughout history, declarations of independence are never in conflict with international law. The judges said that the 20th century declarations of independence have been regarded as compatible and indeed supported by international law in the name of the principal of self-determination. So Crimea's declaration of independence is perfectly valid, as valid as it was the United States declaration of independence from England.