The Islamic State no longer holds any significant ground in Syria and Iraq. What is left of it in a few towns of the Euphrates valley will soon be gone. Its remnants will be some of several terror gangs in the region. Local forces can and will hold those under adequate control. The Islamic State is finished. This is why the Lebanese Hizbullah announced to pull back all its advisors and units from Iraq. It is the reason why Russia began to repatriate some of its units from Syria. Foreign forces are no longer needed to eliminate the remains of ISIS.
In its UN Security Council resolutions 2249 (2015) for the fight against ISIS the UNSC was:
"Reaffirming its respect for the sovereignty, territorial integrity, independence and unity of all States in accordance with purposes and principles of the United Nations Charter,There is no longer any "territory under the control of ISIL". Its "safe havens" have been "eradicated". The task laid out and legitimized in the UNSC resolution is finished. It is over. There is no longer any justification, under UNSC Res 2249, for U.S. troops in Syria or Iraq.
...
Calls upon Member States that have the capacity to do so to take all necessary measures, in compliance with international law, in particular with the United Nations Charter, ... on the territory under the control of ISIL also known as Da'esh, in Syria and Iraq, to redouble and coordinate their efforts to prevent and suppress terrorist acts committed specifically by ISIL ... and entities associated with Al-Qaida ... and to eradicate the safe haven they have established over significant parts of Iraq and Syria;













Comment: This is beginning to sound very "Gonna find those WMDs any day now", eh?