The head of a leading US-allied Sunni militia group in Iraq has been arrested in a joint Iraqi-US operation.

Nadhim al-Jubouri and his two brothers were arrested at their home in the town of Dhuliuya "under the charge of terrorism", the US military says.

Nadhim al-Jubouri is a leader in the Awakening Councils, US-sponsored groups that helped cut violence in Iraq after turning against al-Qaeda.

The charges reportedly date back to when he was fighting against the US.

Iraq's Shia-dominated government took over responsibility for supervising the mainly Sunni Awakening militias from the US military on 1 April.

Many of the Awakening members had been fighting against the Americans but joined forces with them in 2006 to take on al-Qaeda.

Awakening leaders have complained that they have been subjected to growing attacks from insurgents recently and that the government is falling behind in paying their salaries.

This story is a bit complicated when it comes to it's timeline.  The one thing that is not complicated is that the Sunni-Shia divide is as great as it ever was.  It appears that it will not take much to fracture the tentative relationship between the two parties.  For all of the lives and treasure spent on the Iraq War the US has never been able to create a landscape were the Sunnis and Shias willingly unify for the greater good of Iraq.  Each side takes action with their particular self-interests at the core of their decision making.  Ultimately the civil war that raged a couple of years ago in Iraq is still simmering below the surface.  The US was, and is still not, able to help form a singular Iraqi institution which looks after all of the Iraqi people's interests.  Instead the lines dividing that country remain entrenched.