The Monday night statement from the White House accusing Syria of planning a chemical weapons attack was entirely baseless, according to the Syrian Foreign Ministry, which says they believe the US invented the allegation as a justification for another US attack.
That’s the interpretation a lot of analysts are taking as well, as the White House statement was hastily released, and both the Defense and State Departments claimed no advanced notice of it. The allegations therein also included no specific evidence, or even suggestion of where the White House got this putative intelligence, focusing mostly on threatening revenge attacks.
The US used an accused chemical weapons attack in April as a pretext for a large cruise missile strike on a Syrian air base. The Organization for the Prohibition of Chemical Weapons has confirmed the April incident involved sarin, but did not attribute it to one side or another. ISIS has a substantial chemical weapons program, and has repeatedly used it in both Iraq and Syria.
US officials have insisted that they will blame all chemical attacks inside Syria on the Syrian government, despite this very visible enemy faction also having chemical arms. The US has added that they will hold Iran and Russia responsible for resisting US demands for regime change.