Over the course of the war, nearly 4,500 U.S. troops and an estimated 120,000 Iraqi civilians lost their lives, although a recent study suggested the real number of Iraqis who died as a result of the war could be as high as 500,000.
Now, Iraq’s government remains half-formed after an April election and unable to confront the militants led by Islamic State in Iraq and Syria (ISIS) who have taken over cities, including Fallujah, Ramadi, Mosul and Tikrit.
Here are some of the key individuals and groups that played a role in Iraq’s slow unraveling, from the beginning of the war to the present day.
When coalition forces invaded Iraq in March 2003, Saddam Hussein’s army was estimated to number between 300,000 and 350,000 troops. After Saddam was toppled, the Bush administration appointed L. Paul Bremer in May 2003 as Iraq’s top civilian administrator.
Within days of his appointment, Bremer issued Order Number 2 — a directive to dismantle the entire Iraqi army, which was predominantly Sunni. The move shocked the army, and also took U.S. commanders by surprise. “Now you have a couple hundred thousand people who are armed because they took their weapons home with them, they know how to use the weapons, who have no future and have a reason to be angry at you,” Col. Thomas Hammes told FRONTLINE.
The United States spent an estimated $25 billion on training and equipment for new security forces between 2003 and September 2012, according to a report from the special inspector general in Iraq. In 2013 alone, the Iraqi government spent an estimated $17 billion on its security forces.
And yet, this past June, when confronted in Mosul with a much smaller force of around 1,000 armed militants from ISIS and its Sunni allies, Iraq’s army crumbled. Multiple reports described uniforms and weapons discarded by Iraqi soldiers during their hasty retreat from Iraq’s second-largest city.
What happened? The disintegration was gradual, but there were warning signs. The country’s security forces lacked cohesion, with their loyalties divided along Iraq’s sectarian lines, according to a 2010 report from International Crisis Group.
Prime Minister Nouri al-Maliki further weakened the structure by subverting the chain of command, forming new groups that reported directly to him. He also reportedly created a personal army of sorts out of 4,500 U.S.-trained special forces, nicknamed “Fedayeen al-Maliki.”
After the fall of Mosul, Iraqi soldiers were quoted saying they felt “betrayed,” and “abandoned” by their officers.
Al Qaeda in Iraq
Iraq’s insurgency emerged in August 2003, with the bombing of the Jordanian embassy in Baghdad, followed a few days later by a suicide bombing at a United Nations compound that killed the U.N.’s top envoy in Iraq.
Abu-Musab al-Zarqawi, a Sunni extremist, claimed credit for the U.N. bombing, and in October 2004, his group pledged allegiance to Al Qaeda, taking on the mantle of Al Qaeda in Iraq (AQI).
AQI initially was comprised of recruits from Pakistan, Afghanistan and Egypt. It wasn’t until 2006 that the group’s membership was largely Iraqi, according to The Washington Post. The group — which expressly targeted Shia in an attempt to provoke a civil war — reached its peak in power and violence during the bitter sectarian conflict of 2006 and 2007.
But AQI’s brutality led to its undoing, even as it carried out kidnappings and beheadings.
“The Sunnis of Anbar and the Sunni populations of Baghdad had figured out that Al Qaeda was just too extreme to deal with,” said Douglas Ollivant, who oversaw Iraq policy at the National Security Council under both Bush and Obama. “They wanted to marry into their families. They were insisting they maintain a very strict Sharia.”
AQI’s heavy-handedness drove some Sunni tribes, who became known as the Sons of Iraq, into an alliance with the Americans (see below).
On June 7, 2006, Zarqawi was killed by a U.S. airstrike. Abu Ayyub al-Masri became the new leader and renamed the group the Islamic State of Iraq in October 2006. Masri and another top leader were killed in April 2010.
Sensing an opportunity, the group entered the Syrian conflict in 2011, once again rebranding itself, this time as the Islamic State of Iraq and Syria (ISIS).
While ISIS was fighting President Bashar al-Assad’s forces in Syria, it was left alone, according to Ollivant, and “allowed to metastasize into something very, very new and very, very different.”
“This time, it’s Al Qaeda version 6.0,” said Ryan Crocker, a former U.S. ambassador to Iraq. “They make [Osama] bin Laden’s 2011 Al Qaeda look like boy scouts. They are far stronger, they are far more numerous. They have thousands who hold foreign passports and require no visas to get into the United States or other western countries. They are well funded, they are battle hardened and they are well armed. And they now control far more territory exclusively than bin Laden ever did. They have the security, they have the safety to plan their next set of operations and they are a messianic movement. Believe me, they are planning those operations.”
In July 2014, ISIS declared a caliphate in territory seized from Iraq and Syria and renamed itself again — this time as the Islamic State.
The Sunni Awakening/Sons of Iraq
The so-called Sunni Awakening movement began when the Sunni population in Anbar province, some of them insurgents who had fought against U.S. troops, tired of AQI’s excesses.
Gen. Petraeus, who was then leading U.S. forces in Iraq and implementing the counterinsurgency strategy that became known as the “surge,” decided to try to exploit this wedge.
“They’d gotten tired of Al Qaeda,” Petraeus told FRONTLINE. “Al Qaeda had been abusive. It had been blowing Sunni Arabs up and Sunni mosques up, in addition to Shia Arabs and mosques. And so they were keen to get these individuals out of their areas.”
As part of his plan, Petraeus promised the Sunnis a role in the government — and he agreed to pay them, ultimately spending $400 million on what became a paramilitary group he called the “Sons of Iraq.”
“Ultimately, we had 103,000 former insurgents and actually over 20,000 former militia members, part of that 103,000, to give you a sense of the magnitude of this endeavor,” Petraeus said.
Prime Minister Maliki, who was never comfortable with the Sons of Iraq, eventually stopped paying them after the Americans left. In the years following the U.S. withdrawal, the Sunnis who had joined the Sons of Iraq grew angry as Maliki’s government targeted prominent Sunni politicians and cracked down on Sunni protesters.
Radical cleric Muqtada al-Sadr became the face of Iraq’s largest and most feared Shia militia, the Mahdi army, as early as 2004. Deriving his power from his father — a much-revered and “martyred” Shia cleric — Sadr rallied his followers to kick coalition forces out of Iraq, calling the United States, the “great serpent.”
Sadr’s relationship with Maliki has been volatile. He reluctantly backed Maliki as prime minister in 2006 and 2010 in exchange for government positions for his Sadrist political bloc. But he was also quick to withdraw support each time — in 2007 over Maliki’s refusal to come up with a timeline for U.S. troop withdrawal, and in 2012 over Maliki’s alleged dictatorial abuses.
Sadr’s Mahdi army repeatedly clashed with U.S. and Iraqi security forces, starting with fierce fights in Najaf in August 2004. By 2006, the Mahdi army had stormed mosques, thrown out moderate clerics and reportedly threatened the lives of [Grand Ayatollah Ali] al-Sistani and other moderate ayatollahs. Sadr’s militia was also accused of slaughtering Sunni civilians during the height of sectarian violence in 2006 and 2007.
Maliki and Iraq’s security forces moved against the Mahdi army in March 2008, launching a campaign to drive the militia out of its strongholds in Basra and Sadr City. In August 2008, Sadr had ordered the Mahdi army to disarm, and it remained largely inactive for awhile.
Sadr returned to Iraq in 2011, as U.S. troops prepared to withdraw and the Sadrist movement made political gains. Although his party held 40 seats in Iraq’s Parliament and seven ministry positions, Sadr announced in February 2014 that he was withdrawing from politics. Observers noted at the time that Sadr has made similar pronouncements before, only to return.
The fall of Mosul and other cities to ISIS prompted mass rallies of Shia militias who called themselves the “Peace Brigades.” But analysts have suggested the new outfits are a reincarnation of Sadr’s Mahdi army, with a new name designed to distance itself from the tarnished reputation it earned in 2006 and 2007.
Grand Ayatollah Ali al-Sistani
Grand Ayatollah Ali al-Sistani is known as Iraq’s most influential Shia cleric. Described as a “recluse” who shuns the spotlight, Sistani has generally wielded his influence to encourage calm in Iraq.
In 2003, Sistani threw U.S. plans for a rapid transfer of power into disarray when he called for direct elections. He also said Iraq’s constitution must be written by an assembly elected by Iraqis, not appointed. At the time, a New York Times article noted, “Ayatollah Sistani has been tolerant of the United States occupation and has refrained from openly criticizing the occupation authorities.”
In 2004, Sistani negotiated a truce between Sadr’s Mahdi army and U.S. and Iraqi forces fighting in Najaf. Sistani’s influence was such that Al Qaeda in Iraq’s then-leader Zarqawi called for his death in 2006.
Days after the fall of Mosul in June, Sistani called on Shia followers to take up arms to defend “the country, the citizens and the holy sites” against ISIS and its allies. He later adjusted his statement, saying the appeal “was not only about one sect.”
That month, Sistani called for the formation of a government with “broad national support,” phrasing that many interpreted as a rebuke of Maliki’s sectarian politics.
Sistani again indirectly called on Maliki to step aside on July 25, saying that political leaders should not “cling to positions or posts,” but should have a “spirit of national responsibility.” Two days later, Maliki’s own party released a statement echoing Sistani’s language urging politicians not to “cling” to their positions.