Miles O’Brien:

The long fight against ISIS in Iraq is now all but over. Claiming victory? An American-led coalition of Iraqi government forces and Kurdish troops, joined by tens of thousands of militia fighters backed by Iran.

And it is the Iranian support for that force that is causing great concern in Washington.

We return to our series Iran Rising in Iraq.

And again, in a partnership with the Pulitzer Center on Crisis Reporting, special correspondent Reza Sayah reports.