An offensive by fighters linked to al-Qaeda in western Iraq is challenging the authority of Prime Minister Nouri al-Maliki, and testing local loyalties.
There may be some challenges in reconciliation between the Sunnis in Anbar and the central government, but that's a low-level political matter that needs to be worked out in the long run. The near-term existential threat to Iraq, and in particular to the Sunnis in Anbar, is the presence of al-Qaeda .... The key element now is to defeat al-Qaeda.
The Islamic State of Iraq and the Levant, known as ISIL, has taken over parts of Fallujah and Ramadi, which are both Sunni strongholds in Anbar province.
Fighters are reported to have stormed police stations, seized weapons, freed prisoners, and set buildings on fire.
The group is said to be supported by local Sunni tribal fighters and has been bolstered by cross-border ties with its affiliate in Syria.
Iraqi government forces have been accused of failing to get a grip on security since US troops pulled out of the country two years ago, with 2013 cited as the deadliest year in Iraq since 2008.
Some Sunni's also claim they have been marginalised, and accuse Maliki's Shia-led government of discrimination.
Even so, while some tribal militias are supporting ISIL, others are backing the security forces, making for a complex three-way fight.
It harks back to the days of the so-called Sahwa militia or Awakening Councils when Sunni tribesmen turned their guns on al-Qaeda, opting to support US troops instead.
Speaking in a televised address, Maliki tried to present a united front.
''The people of Anbar province are now standing shoulder to shoulder with the Iraqi armed forces. This is the true stance of Iraqis. They [the people of Anbar province] are once again carrying weapons to chase al-Qaeda members. This is the real attitude of Iraqis .... [There will be] no retreat, until we eliminate this gang [al-Qaeda] and rid the people of Anbar of their [al-Qaeda members] evil acts," he said.
Al-Qaeda is taking control of parts of Fallujah. Fallujah is going to be like an abscess collecting parts from all over Iraq, a magnet for the jihadists, for terrorists to come over there. Then the abscess has to be lanced at some time. And I believe the Iraqi security forces are on this job.
John Kerry, the US secretary of state, said his country would stick by Iraq, but ruled out sending back any troops.
He called ISIL "the most dangerous players in the region", and said: "We will stand with the government of Iraq and with others who will push back against their [ISIL] efforts to destabilise. We are going to do everything that is possible."
ISIL is made up of a variety of groups and clans of Sunni faith which rose to prominence after the US invasion of Iraq in 2003.
It became known as Al-Qaeda in Iraq a year later, after pledging its allegiance to the group. It aimed to establish a single state based on Sharia, or Islamic law, in Sunni-dominated regions of Iraq.
This was later expanded to Syria, with the name amended to its current title in April last year.
ISIL is one of the strongest rebel units fighting government forces in Syria, but it is facing opposition from an alliance of other rebel groups which resent what they see as ISIL's harsh interpretation of Islamic law.
So, why is ISIL in control of parts of the west of the country? Is this fight in Anbar province a sign of a much bigger problem for the Iraqi prime minister? Should the US interfere? And how much of a threat do fighters linked to al-Qaeda pose to Iraq and Syria?
To discuss this, Inside Story presenter Dareen Abughaida is joined by Mark Kimmitt, a retired brigadier general in the US army, and former military spokesman for coalition forces during Operation Iraqi Freedom; Mowaffak Alrubaie, a former Iraqi national security adviser and aide to Prime Minister Nouri al-Maliki; and Salah Hashimi, a legal adviser to the Iraqi League, a UK-based rights group.
"Prime Minister al-Maliki used the oldest trick in the book: He went over to America and said 'please help me with weapons and whatever I need in order to fight terrorism'. And when the Americans responded he went back and flew a few planes over the desert of al-Anbar, firing a few missiles at some targets ... he said that they were al-Qaeda .... I think the situation now is very critical .... As a country, we need to have strong and effective security forces in order to fight external and internal threats .... But there are double standards."
Salah Hashimi, a legal adviser to the Iraqi League