An intentional signal to Putin that there would be no US war with Russia to defend Ukraine?

Obama on the World

Some people think it's sometimes best for others not to know your intentions.

But sometimes, on the other hand, the risks of misunderstanding are much too great.

From the piece.

Despite Western sanctions, he [President Obama] cautioned, President Vladimir Putin of Russia “could invade” Ukraine at any time, and, if he does, “trying to find our way back to a cooperative functioning relationship with Russia during the remainder of my term will be much more difficult.” 

Or is this a blunder, like Acheson leaving South Korea on the wrong side of the boundary within which the US was pledged to "contain" Communism?

Or that silly woman who gave Saddam a "green light" to invade Kuwait?

I note in passing that, unsurprisingly, neither liberal interviewer nor liberal president entertains the notion that the fundamental blunder in Syria, like that in Egypt and even in Libya, was the same as the blunder in Iraq.

Knocking off a secular and moderately irritating dictator when it is foreseeable that he will only be replaced by worse is just stupid.

Faced with the fact that Assad in Syria will not be replaced by anyone much more acceptable than ISIS, neither of these fellows admits that our destabilization of his regime was an error and that even now we must hope that he will win, whether or not we actually do anything directly to help him.