However, there were already signs that the group was losing momentum. From 2006, other Sunni militant groups publicly criticised AQI for aggressively trying to unify the insurgency under its command, sometimes by killing members of rival organisations. Sunni Arabs began to complain that the foreign-led extremist group was trying to impose its draconian interpretation of sharia law in areas under its control, forcing young women to marry its fighters and killing anyone who opposed it.

Sunni Arab opposition to AQI coalesced into the ‘Awakening Movement’ and its associated Sons of Iraq militias, which recruited fighters from other insurgent groups. Backed by the US military, these militias proved highly effective at rooting out Al-Qaeda fighters from their local communities. Members of the Awakening Movement increasingly became the target of suicide bombers, but the attacks appear to have solidified Sunni Arab opposition to AQI, rather than weakened it.

US intelligence sources told that there are only between 800-1,000 members of AQI left. However, Fawaz Gerges, a professor of international relations at the London School of Economics, told that this figure was probably inflated and that AQI had "suffered a strategic defeat in the last four years or so."

AQI’s international support dropped off as its reputation was damaged by Sunni opposition in Iraq. US officers told that only around 10 foreign fighters were crossing into Iraq every month in 2008, even though the country’s borders remained porous.

In September 2011, Major General David Perkins, the outgoing commander of US forces in northern Iraq, told journalists that intelligence and the growing involvement of Iraqis in suicide bombings, which were historically almost always carried out by foreigners, showed there had been "a dramatic drop-off in the foreign fighter flow coming into Iraq".

In October, Major General Diya al-Kinani, the Iraqi Ministry of the Interior’s director of counter-terrorism operations, told Al-Arabiya TV that the number of foreign fighters joining AQI had decreased further due to the unrest in neighbouring Syria. However, he noted that a Saudi was now the group’s leader for the Baghdad region, having taken over from Huthaifa al-Batawi, who was arrested in November 2010 and latter killed in a prison uprising.

Maj Gen Perkins said that foreign financial aid has also decreased and that AQI was resorting to extortion, black marketing and robbery to finance its activities. "It’s evolving into almost gang mafia-type activities," he said. He added that the dramatic decrease in the group’s ability to raise funds had resulted in internal disputes over how money is distributed.

Baha al-Araji, head of the Shia Ahrar parliamentary bloc, announced in October that there was evidence that some private banks were financing terrorism. "There is clearly confirmed information

indicating that some private banks have financed terrorist groups and Al-Qaeda in their military operations against the Iraqi people," he told a press conference.

AQI has become a more Iraqi organisation as its foreign support has ebbed away, albeit one that still associates itself with the wider Al-Qaeda movement.

After Zarqawi’s death in June 2006, AQI announced that Abu Hamza al-Muhajir had taken over as leader. The US identified him as Abu Ayyub al-Masri, saying he was a veteran member of Ayman al-Zawahiri’s old Egyptian jihadist faction. In November 2010, a Kuwaiti newspaper published transcripts of the interrogations of another Egyptian jihadist detained in Yemen who identified Abu Hamza as Abd-al-Munim al-Badawi and said the US incorrectly believed he was known as Abu Ayyub because he had a forged passport in the name of a jailed Egyptian jihadist who used that nom de guerre. The detainee said that Badawi was very close to the Al-Qaeda leadership, with Osama bin Laden describing him as ‘the legend’ for his intelligence gathering capabilities.

Abu Hamza was ostensibly demoted when AQI announced the formation of the Islamic State of Iraq in October 2008. He officially filled the roles of ‘minister of war’ and ‘prime minister’ in the new organisation, which was led by the Iraqi Abu Omar al-Baghdadi.

The US initially said Abu Omar was a fictional leader who had been invented to put an Iraqi face on the foreign-led group. However, it subsequently emerged that Abu Omar was an Iraqi preacher from Al-Anbar province called Hamid Dawud Muhammad Khalil al-Zawi who had established himself as a leader in his own right.

After Abu Hamza and Abu Omar were killed together in April 2010, the group announced that Abu Bakr al-Baghdadi al-Husayni al-Qurashi had taken over as emir and Al-Nasir Li-Din Allah Abu Sulayman as war minister, both of whom maintained an even lower profile than their predecessors. The group has said that this is for security reasons in a ‘press conference’ statement released in April.

In January, Major-General Diya Husayn Sahi, the Ministry of Interior's director of counter-terrorism, identified Abu Bakr as Dr Ibrahim Awwad al-Samarrai and Abu Sulayman as Numan Salman Mansur al-Zaydi. The later was killed in Al-Anbar province the following month. The US government named Awwad Ibrahim Ali al-Badri (alias Abu Dua) as the group’s leader in October when it designated him as a terrorist and offered a USD10 million reward for information on his whereabouts. It listed Dr Ibrahim Awwad al-Samarrai as an alternative name.

A few days after the designation, Maj Gen Kinani told Al-Arabiya that Badri was born in Samarra in 1971, is married to a woman from Al-Fallujah, has four children and obtained a PhD in Islamic law from Baghdad’s Islamic University in 2006. He was detained by US forces in 2005, but released after a year, then served as the spiritual leader of AQI until his promotion. When asked why such a dangerous man was freed, Maj Gen Kinani said: "US forces arrested and released many leaders of Al-Qaeda simply because people at that time were arrested without arrest warrants."

Maj Gen Kinani dismissed the idea that Badri is an Iraqi front man for foreign leadership. He said AQI is a devolved organisation where local leaders "can plan for an operation and notify the organisation

of it without the need to obtain authorisation from the central command." He said most of these regional leaders have "pledged allegiance to al-Badri".

Maj Gen Kinani added that Badri had been in touch with Bin Laden before his death. "The two men were exchanging messages on the organisation and its plans to carry out operations in Europe and the United States," he said. While AQI has not been held responsible for any attacks outside Iraq since it bombed hotels in Jordan in November 2005, Maj Gen Kinani said in January that that Taimour Abdulwahab al-Abdaly, the Iraqi-Swede who killed only himself in a botched bombing in Stockholm on 11 December, had been trained in Iraq. He said a detained ISI leader had confirmed that Abdaly had "entered Iraq through Turkey, reached Mosul and spent three months in training in Mosul."

AQI’s desire to continue to be associated with Al-Qaeda was reflected in its response to the death of Bin Laden. Within days, the group had released a statement written in the name of Abu Bakr to praise the Al-Qaeda leader and appeared to recognise Zawahiri as his successor weeks before it had been officially announced. "I tell our brother in Al-Qaeda led by Ayman al-Zawahiri, go on with God’s blessing and be glad that you have faithful brothers in the Islamic State of Iraq who are marching on the path of right," it said. Major-General Jeffery Buchanan, the spokesman for US forces in Iraq, told : "There was no reaction from Iraqis to the death of Bin Laden. However, AQI was the first regional node to eulogise him."

AQI released a cooler statement after Zawahiri’s official appointment. In an audio recording released in August, Abu Muhammad al-Adnani, the group’s official spokesman, swore allegiance to Afghan Taliban leader Mullah Omar Mohammed, not the new Al-Qaeda leader. Abu Muhammad only congratulated Zawahiri on his appointment as the new Al-Qaeda leader and wished him luck, indicating that AQI does not want to present itself as a subordinate organisation.

Maj Gen Perkins described the AQI network as "not ineffective, but highly degraded." He said this had manifested itself in a dramatic decrease in attacks, especially spectacular "Al-Qaeda signature" suicide bombings. "We see now more vehicle-borne explosive devices that are parked and detonated, versus being driven and detonated, which means they’re having a hard time getting people who are true believers [to carry out suicide attacks]. It’s less effective when they can’t drive the vehicle in."

US officers stress the progress that has been made in rebuilding Iraq’s military and security forces since 2003. Maj Gen Buchanan told : "One element that is not massively understood is the increase in the size and capabilities of the Iraqi security forces since 2003. I was there eight years ago when the first battalion graduated and the Iraqi army had 500 troops. Now it has 650,000 and the quality is much improved. Every year they get a little bit better."

However, speaking off the record several US and Iraqi officials have said that there was behind-the-scenes support for maintaining a US military presence in the country beyond the 31 December deadline set down in the status of forces agreement. President Obama’s announcement that all US troops would be withdrawn indicated that negotiations to amend this agreement had failed to overcome the political barriers. The US will still maintain a massive diplomatic presence that will be largely protected by private security contractors rather than US military personnel.

There is concern that, despite their progress, Iraqi security forces will struggle to maintain pressure on AQI and the other militant groups. Maj Gen Perkins said that, since the US military had officially ended its combat operations, one of the most important roles it had played in supporting Iraqi security forces was "intelligence fusion". Without this support, Iraq’s numerous and often disjointed

security and military organisations may struggle to share the information they have gathered and co-ordinate their operations.

Iraq’s aviation capabilities also remain underdeveloped. It currently has only a handful of propeller-driven aircraft capable of carrying out airstrikes and a small fleet of Mi-17 helicopters providing tactical air lift, but not during the night.

Maj Gen Buchanan admitted that the Iraqi security forces "still need more work" and that the "the US are the primary enablers of operations - providing aircraft, intelligence, refined targeting and medevac facilities... it seems inevitable that there will be a change in the both the quantity and quality of Iraqi security forces counter-terrorism operations."

There are also concerns about the Iraq’s Shia-dominated government’s commitment to the Sons of Iraq militias that were so central in degrading AQI. The government has promised to integrate the Sunni militias into the official security forces or find them alternative employment. Members of the Awakening Movement have long complained that the government only begrudgingly pays the militias and that the process of transition has proceeded slowly.

Maj Gen Buchanan said: "There are no pay complaints from anyone who is not legitimately on the books. The original Sons of Iraq number was 100,000 and about 50,000 have transitioned, leaving 50,000 left spread across nine provinces and not all Sunni. The Iraqi government is concerned with their transition". A senior Iraqi politician contested these figures, telling that the militias "are now being sidelined and marginalised. Only 20% have been incorporated into the state".

Meanwhile, AQI has seemingly softened its stance on the Awakening Movement. In the audio recording released in August, Abu Muhammad al-Adnani said: "As for you satanic Awakenings, we strive to guide you more than you strive to kill us. If you come to us in repentance, we will accept your repentance even if you killed a million people."

More generally, there remains widespread frustration with the government in Iraq’s once powerful Sunni Arab community. Speaking off the record in October, a senior Iraqi politician told Jane’s that the de-Baathification process to purge members of the former regime from state institutions was "an inquisition, which was abused for the sake of vengeance. Shia Baathists stay in senior positions, while senior officials from Diyala were sacked recently just for being Sunni... The lack of balance means that Iraq is like a bird flying with only one wing. We need to re-establish the political balance".

On 29 October, Iraqi Prime Minister Nuri al-Maliki announced that 615 people had been detained in a security sweep targeting members of the former ruling Baath party. Actions like this lead observers such as Professor Gerges to say that he is "less worried about the remnants of AQI than about the response of the Sons of Iraq to greater sectarianism in the government."

The extent to which sectarian tensions escalate in the wake of the US withdrawal remains to be seen, as does AQI’s ability to capitalise on any increase in Sunni frustration. While the group’s stringently anti-Shia religious rhetoric may help it to attract support, its record of killing fellow Sunnis may make it hard for it to rebuild. Ansar al-Islam may be in a better position as it uses similar religious rhetoric, but is not so tainted by a history of attacking fellow Sunnis. The group is now

releasing slicker propaganda videos than AQI that promote it as a technologically sophisticated force. Meanwhile, JRTN uses a more nationalistic narrative condemning what it perceives as the pervasive Iranian influence in Iraq.

Even if it does not become the primary vehicle for Sunni discontent, AQI may find enough breathing space in the wake of the US withdrawal to organise a major attack that significantly destabilises Iraq, much as the Al-Askari Mosque bombing did in 2006. Scenarios include major attacks on religious locations and ceremonies, or the assassination of senior Shia politicians or figures such as the Grand Ayatollah Ali al-Sistani, which could spark renewed sectarian conflict.

An example of how terrorism can spark a wider sectarian confrontation was seen in September, when suspected AQI militants killed 22 Shia pilgrims in Al-Anbar province. The government’s decision to deploy national forces to arrest eight local suspects sparked angry protests across the province. Eventually Prime Minister Maliki had to get involved, condemning what he called "irresponsible statements that may lead to igniting sedition between Al-Anbar and Karbala provinces."

AQI will live on after the US withdrawal even if fails to gain much momentum. It has been the focus of years of intense combined counter-insurgency operations by US and Iraqi forces, even as its reputation as a credible Islamic organisation has been severely undermined. Yet it has survived and continues to periodically make its presence felt. Professor Gerges told : "AQI can be successful in ensuring a level of continued instability in Iraq, which I envisage as being the case for the next five to six years."

James Denselow is a writer on Middle East geopolitical and security issues based at Kings College London. He is a Director of the independent research institution and consultancy the ‘New Diplomacy Platform’. Translation support provided by Sarah Bradley.