Conspiracy theory, no evidence given. The US is leading the global coalition to defeat Daesh. http://www.inherentresolve.mil/campaign/
U.S.-backed militias are fighting the Daesh in its former Syrian headquarters of Raqqa. Islamic State has lost much of its territory in Syria this year under separate offensives by the SDF (US-backed militias under the banner of the Syrian Democratic Forces) and the Russia-backed Syrian military. https://www.reuters.com/article/us-mideast-crisis-syria-raqqa/syrian-militias-aim-to-push-islamic-state-out-of-raqqa-within-a-month-idUSKCN1C01RZ
Background on the fight against Daesh: https://www.crisisgroup.org/middle-east-north-africa/eastern-mediterranean/syria/b053-fighting-isis-road-and-beyond-raqqa