Gun battles and deadly clashes have broken out across Iraq, after government security forces stormed a Sunni protest camp.
This has ignited a wave of violence across the country, and raising fears of a return to sectarian fighting that left tens of thousands dead just a few years ago.
What happened in Al-Hawija … it's a massacre, it's a genocide against the Iraqi people ...
It is the bloodiest fighting yet since thousands of Sunni Muslims started holding demonstrations against the Shia-led government in December.
Sunni protesters accuse the government of discrimination and neglect, and pursuing a sectarian agenda. They are also calling for the resignation of prime minister Nouri al-Malaki.
It is all serving to pose a stubborn challenge to Iraq's stabliity - a decade after the toppling of Saddam Hussein.
The focus of the security operation was an encampment in the northern town of Hawija. The government says it was a response to an earlier attack on a police and army checkpoint.
News of the raid quickly spread to other Sunni areas - security forces were attacked in Ramadi and Fallujah, and in Suleiman Beg and Mosul.
In the past four months, tens of thousands have taken to the streets of Iraq's Sunni majority provinces of Anbar, Nineweh, Sala-heddin, Kirkuk and Dyala - demanding an end to what they call second-class treatment by Iraq's Shia led government.
There is absolutely no indication that this is a sectarian issue, it is between peaceful demonstrators and a government which happens to be dominated by Shia elements in Iraq ...
This struggle goes back many years - under Saddam Hussein, power was concentrated in the hands of Sunni Muslims, but that dynamic changed following the US-led invasion of Iraq in 2003.
And between 2005 and 2007, sectarian and intercommunal fighting pushed the country to the brink of civil war, when violence claimed tens of thousands of lives.
But the big test for Iraq came when the last US troops pulled out in December 2011 - violence did ease, but there has been squabbling since then among Shia and Sunni, and also Kurdish parties about how to share power.
The political indecision has rekindled simmering frustrations, leading to this latest Sunni protest movement.
on the other hand, the US has been worried that Iraq could be sucked into the conflict in Syria, where a Sunni-led rebellion is fighting against Bashar al-Assad's government.
And Sunni fighters from Iraq are said to have joined that fight, whereas Iraq's government supports al-Assad.
The US is concerned that flights from Iran, through Iraqi airspace, may be supplying weapons to Syria. It is raising fears of wider regional instability.
So is this conflict a sectarian one? What solutions can be implemented? And can a conflict-free Iraq facilitate wider regional instability?
Inside Story, with presenter Laura Kyle, discusses with guests: Abdulmunaem Almula, a London-based Iraqi affairs analyst and protest organiser; Phyllis Bennis, a director at the Institute for Policy Studies, and adviser to UN officials on Middle East issues; and Salah Hashimi, a lawyer and spokesman for the Iraqi League in the UK.
"[The ]Iraqi civil society has been in motion in extraordinary, impressive ways. Yes it’s been non-violent, but that’s not the only thing , it has also been broad-based ... challenging the existence of a sectarian government system that was put in place by the United States at the very beginning of its occupation."
- Phyllis Bennis, director at the Institute for Policy Studies