The Symbolic Value Of Mosul's Secret Resistance

Compared to the industrial slaughter carried out by the Islamic State death cult, their work is artisanal.

Homemade napalm engulfs a house... a bearded man is shot in the head with a pistol mounted with a makeshift silencer... an idle sentry is picked off.

Video images, exclusively obtained by Sky News, were taken in the rush and chaos of brutal attacks by Mosul's resistance movement - targeting the agents of the city's Islamic State (IS) officials.

The small cells, unknown to one another, have been arming themselves with weapons from the black market.

They recruit only people they know and trust. And it's unlikely that they are able to do much more than catch a few members of the IS hierarchy off balance.

But their actions have a powerful and important symbolic value.

Grandly calling themselves the Mosul Brigades, they are mostly, and importantly, Sunni Arabs.

The majority of Mosul's two million population is Sunni.

They are deeply fearful and distrustful of Baghdad where the government is not only dominated by Shi'a but increasingly dependent on Iranian military advisers and other aid.

This, in turn, underpins the government's own reliance on Shi'a militia in the fight against IS, or Da'esh as it's known in the Middle East.

Atheel Nujaifi, Mosul's governor until Islamic State rolled into the city almost unopposed last June, said: "In Mosul no one is sure how they will be dealt with after the city is liberated. We need a discussion about this with the government in Baghdad."

Shi'a militia are said to have carried out revenge attacks and sectarian killings in areas they helped liberate near Tikrit.

IS has been quick to exploit these atrocities - refugees from those areas have been encouraged to tell their stories by their jihadi overlords.

But the small cells from the Mosul Brigades remind not only their neighbours in the city, but the wider Iraq, of two things:

That IS is as bitterly hated by most Sunnis as anyone.

And if the second largest city in Iraq is to be liberated, it will only be possible by harnessing local people to the cause.

The unpicking of IS's invincible image by local resistance cells also serves as a signal to rival sectarian militia to stay away.

"We are ready, as soon as we know what the future deal is, to begin the liberation," the former governor told Sky News.

His problem is that Baghdad's eyes are on Anbar Province where IS has been lapping at the edge of the capital - and even with coalition air strikes its efforts have been patchy in success.

Far away in the north of the country Mosul's future is likely to be left well down the list of priorities.

Just as it was when IS stormed in last June.

Until it floats into focus more sharply, the small, secret teams of homegrown resistance remain the only sign that Mosul isn't collapsing into apathetic acceptance of life under the shadow of IS.