None stated. Of course.
But they have stated in the past that US involvement would be to degrade and destroy ISIS.
Now, don't get me wrong...I'm not necessarily opposed to putting 4 Divisions with an extra Artillery Brigade around Mosul and killing every living thing there.
Just not under this POTUS.
That makes sense, of course, but it isn't (as you are aware) an objective. Which is the exact problem with amateur involvement in this sort of thing - you get vague, immeasurable missions with no metric for success and because of that, no end in sight. "Interdict lines of communication" is such a mission. "Take Raqqa and destroy everything useful to the enemy" is an objective. Big difference.
Amateur dilettantes such as 0bama don't want to state objectives that may be measured because of the political consequences of failure to attain them. It is from this that open-ended commitments to do military stuff lead straight into a quagmire. Where we had a defined military objective: "overthrow the Taliban government" or "take down Saddam's government and capture its leaders," then we enjoyed success, probably too rapid and complete for its own good. It gave the political leadership the impression that we could accomplish anything forever. We saw this in Iraq where political and not military considerations led to "Take Fallujah - wait, don't take Fallujah - OK, go ahead, take Fallujah" over a period of months which cost us unnecessary casualties when the enemy had plenty of time to dig in.
I realize I'm preaching to the choir here. It's fairly obvious that our troops have been frequently and systematically misused in the past and I think this is the principal reason why. 0bama and his like have no business at the planning table, and these days they think they own it.