Obama's secretary of state John Kerry says there exists "undeniable" evidence of a recent chemical weapons attack in Syria. Of course he's not actually saying it was the Assad government behind the attack. There are plenty of Bad Actors afoot in Syria who might have been willing to do some pretty horrific things to drag the West in against Assad. So, when it comes to establishing casus belli, undeniable isn't quite the same as conclusive.
And then there's this guy who also came forward with proof positive of weapons of mass destruction. Oh yeah, he was a secretary of state too. Don't they say the damnedest things? What was this guy's name? Slam Dunk, was that it?