In August 2008, Senator Barack Obama made an impromptu statement about the invasion of Georgia by Russia which had happened earlier in the day. A clearly bothered Obama was about to leave for vacation in Hawaii and his statement was jumbled and at points contradictory.
Today, he made a similar statement about Putin's invasion of the Crimea. While Obama's speech was without as many stutters, it was still hollow on rhetoric and without the emphasis to prevent further Russian actions. To paraphrase Charles Krauthammer today: Obama told the world that he would take no serious action to check Russia. Obviously Obama should have listened to Sarah Palin.
Taking a look at both statements shows why Putin thinks that he can get away with a 2008 redux.