A leaked conversation between two people in the US security apparatus flat-out asserts, as a certainty beyond question, that Assad didn't launch a sarin attack this year, and that the US security apparatus knows that for certain.

I am not sure what to make of this dialogue.

On the one hand, I have some respect for Seymour Hersh, who published this. The idea that the troll lied about the sarin attack, having lied about so many other things, is not a priori implausible.

On the other hand, this is supposedly a leaked conversation between two people, but it doesn't read like a conversation. It reads like a two-speaker joint presentation to an audience.

As a result, I feel unable to judge what part of this is true.

The OPCW announced some more evidence that the poison was Sarin and that it spread from a Syrian munition.