Robert Burns of the AP reports that:
About half of Iraq’s army is incapable of partnering effectively with the U.S. to roll back the Islamic State group’s territorial gains in western and northern Iraq, and the other half needs to be partially rebuilt with U.S. training and additional equipment, the top U.S. military officer said Wednesday.
The inadequacy of the Iraqi army implies, necessarily, a need for it to be trained up, with Americans doing the training. But:
renewed U.S. training effort might revive the issue of gaining legal immunity from Iraqi prosecution for those U.S. troops who are training the Iraqis. The previous Iraqi government refused to grant immunity for U.S. troops who might have remained as trainers after the U.S. military mission ended in December 2011.
Which bring things back around to that never negotiated status-of-forces agreement and the failure to leave a core U.S. presence in Iraq.