Fall of Ramadi to Islamic State opens up deep-seated and worrying problem at heart of whole region's politics

US Secretary of State, John Kerry, says he is confident that the Iraqi government will retake the central city of Ramadi from so-called Islamic State.

But he knows that even if this was to happen, the way Ramadi fell and how it could be re-captured opens up a deep seated, worrying and long-term problem not only at the heart of Iraq's crisis - but at the heart of the whole region's politics.

Ramadi is the capital of Anbar province, not only the biggest province in the country, but the heartland of the country's Sunni community.

Anbar was the heart and soul of so-called Sunni Insurgency against US forces in the wake of the 2003 invasion and occupation of Iraq.

It was in towns and city's like Ramadi and Fallujah that al-Qaeda relationship and partnership with the disaffected and marginalised Sunni tribes, many of whose members made up the officer corp of Saddam Hussein's military, was forged.

IS is following the same strategy as al-Qaeda in Iraq did by allying itself with a Sunni community aggrieved at the openly sectarian policies of an almost wholly Shia dominated government in Baghdad.

As soon as IS captured Ramadi it ransacked the miltiary headquarters, seizing large amounts of equipment and killing any government and tribal leaders who'd remained loyal to the government.

But it's what happened next that is so worrying and so telling.

Realising that government troops had, like so often before, simply run away rather than defend the city, the provincial government of Anbar appealed to the Baghdad government to retake the city by sending, not more government troops, but the Shia militia trained and in many instances directed and controlled by Iranian advisers.

This is exactly how Tikrit was retaken earlier this year.

It mirrors in many ways what we are seeing in other parts of the Middle East in turmoil; from the Houthis in Yemen, Hezbollah in Lebanon, as well as Hezbollah and Iranian Revolutionary Guards supporting the Syrian government - it is paramilitary forces with an overtly sectarian identity that is not only being used instead of state military institutions but who are proving to be the most effective.

For Iraq it creates a self-perpetuating sectarian war where the US now ironically is poised to again use its air power in support of a Shia militia trained and led by Iran.