Even if the Iraqi government defeats ISIL, a big question mark still hangs over its ability to re-unify a deeply divided nation.

The Iraqi military appears to have surprised even itself with the speed in which it is re-capturing ISIL held territory. If and when the extremists are finally defeated militarily, some members of the ruling coalition say Iraq will still face the very same sectarian split that led to the rise of the fanatical group in the first place.

“We need better coexistence and understanding of how we all share this land. We need to understand that a representation in the government could be proportional to the amount of social representation,” said Saad Almutalibi, Member of Parliament of State of Law Party.

Under Saddam Hussein Iraq Sunni Muslims dominated high positions in the government and military, jobs overwhelmingly held by Shiite Muslims since the U.S.-led invasion.

After Sunnis led the opposition to U.S. occupation they were largely disarmed leaving them vulnerable and, in some cases, welcoming when ISIL arrived. It now seems unlikely ISIL can be fully defeated by the army alone.

“If the Sunnis are supported, they can form a force to protect the areas liberated from ISIL control,” said Peshmerga Major General Zrian Shekhwasani.

That means arming Sunni tribes, which the government is unlikely to do. But if any good has come from the fight against ISIL, known locally as Daesh, it is that former enemies have been fighting side by side. Then there are the Kurds who want to split from the Shiites and Sunni Arabs.

Iraq is slowly veering away from chaos that has marred the country since 2003, but the sectarian divide remains an obstacle still to overcome on the road to peace and national unity.