To understand what is going on here, one needs to engage is something akin to Kremlinology to figure out what is going on here, but my (not particularly well educated) guess is that there is a conflict between those who want to overthrow the Assad regime (AKA “The Blob”), and those who are OK with Assad remaining in power and want to focus on ISIS/ISIL/Daesh/Whatever. 

Again, I should note that this is a guess, but my guess is that someone in “The Blob” cherry picked some intelligence in in the hope of either fomenting a regime change scenario or an attack on Assad’s ally Iran.

In any case, it looks like there is some deescalation going on now:

Secretary of Defense Jim Mattis claimed Wednesday that the Syrian government backed down after the White House said that Syrian President Bashar al-Assad’s forces were preparing for another possible chemical attack.

“They didn’t do it,” Mattis said.

Speaking to reporters aboard a flight to Brussels, the retired four star general gave few details to support the assertion that the Syrian military stepped back from plans for a possible chemical strike. On Monday, the White House warned that Syrian forces would “pay a heavy price” if they carried out another chemical strike.

Mattis’s remarks come a day after the Pentagon said it had seen “active preparations for chemical weapons use” at Shayrat Airfield, the same place struck by more than 50 cruise missiles earlier this year.

It sounds to me like someone caught the rat-f%$#, and decided that the politic thing would be to declare victory, and go home.

Interestingly enough, Mattis is a big advocate of military action against Iran, so the fact that he is declaring victory is rather puzzling.