In the early years of the rebellion in Syria, when the rebels were not Islamists, Obama stood by and did nothing.
Obama told the world that that would change if Assad used chemical weapons. But when Assad did Obama once again did pretty much nothing; some half hearted support for some rebels.
Eventually in the face of genocide against Christians-- I know that Christians, unlike Jews, aren't a race so technically what ISIS is doing is not genocide but the term fits so I'll use it-- and the collapse of Iraq--due to Obama's premature withdrawal of all US forces-- Obama allowed some limited air strikes which didn't appear to do a whole lot other than let Obama say he was acting. But even those air strikes were against ISIS not Assad's forces.
Now Russia has stepped in and basically said that it will use military force to ensure that Assad stays in power.
And Obama's response is to say that Putin is making a mistake.
If I were Assad I'd be feeling the love from Obama.