Who is the liar? Putin or Obama/Kerry?

 Putin has gone on record to say that the rebels were behind the chemical
attack and not Assad. His commentary was published in the NYT, ‘…there
is every reason to believe it was used not by the Syrian Army, but by
opposition forces, to provoke the intervention by their powerful foreign
patrons, who would be siding with the fundamentalists”.
 
If one is to look at the intent and the outcome