It looks to me like Putin has the facts on his side, ugly as they might be. The West backed the violent overthrow of Ukraine's elected government, so the present Kiev regime is therefore illegal. To defend its own strategic interests against the new, anti-Moscow government in Kiev, Russia has now seized Crimea and allied itself with the breakaway peninsula's heavily Russian population. Logically, the Moscow-leaning eastern half of Ukraine is next.
We may not like what is happening, but we can't support a coup one month and then pretend the following month's counter-coup is somehow illegitimate. The strongest side will prevail and there's not a thing we can do about it. Except talk. And words that cannot be supported with action are better left unsaid, lest their speaker lose all credibility.