In mid-September 2014 the United States released the findings of American military evaluation teams sent to Iraq to find out how much of the Iraqi Army was salvageable. It was discovered that only 52 percent of the 50 Iraqi combat brigades were worth training and supporting in the short run. The other 24 brigades had been rendered ineffective by Shia politics and officers who were too poorly trained, experienced or dedicated to hold these units together in heavy combat. The basic problem was bad officers, in particular officers more interested in politics and getting rich (via corrupt practices) than running an efficient army. This is not a new or unique problem in the Iraqi Army.
The U.S. did much from 2003 to 2011 to build an effective officer Iraqi officer corps. Yet this effort was complicated by religious differences. For example, back in 2010 Iraq reinstated 20,000 Sunni Arab officers that were fired after Saddam Hussein was overthrown in 2003. This was done on the advice of the Americans. The original dismissal was done because the Sunni Arab minority (20 percent of the population), led by Saddam Hussein, had dominated the government, military and economy for centuries. Since the Sunni Arabs did not respond well to losing power in 2003, it was felt that Sunni Arab officers could not be trusted. Until 2010 hundreds of Sunni Arab officers were vetted for loyalty to the democratically elected government (dominated by Shia Arabs) and returned to service. This was often because these officers had unique skills that were much needed in the new, and largely Shia military. By 2010 the Sunni Arab community was down to 15 percent of the population, because so many Saddam supporters had fled the country, in fear for their lives from Kurds and Shia Arabs seeking revenge. More importantly the Sunnis had finally given up their support for Sunni terrorists three years earlier and (most of them, anyway) tried to regain the trust of their Kurdish and Shia Arab neighbors. Many Sunni Arab officers and politicians were still banned, and some had been arrested and prosecuted. But the government felt confident enough in the Sunni Arabs to allow many Sunni Arab officers an opportunity to reapply for jobs in the armed forces. There was a need. But after the Americans left in 2011, the Shia politicians changed their minds and began persecuting the Sunnis once more and replacing the experienced Sunni officers with less experienced, but loyal, Shia.
By 2010, after six years of effort, the Iraqi government had managed to produce a force of over 600,000 armed men. Saddam had at his disposal about twice as many. How did the two forces compare, now that the Iraqis had rebuilt their security forces? And where did the 20,000 Sunni Arab officers fit in?
Before Saddam was ousted in 2003, the active duty army consisted of about 250,000 troops. Some 40 percent of these were the elite Republican Guard, which was all Sunni Arab. In addition, nearly all the army officers, and most of the NCOs, were Sunni Arabs. The Republican Guard, was, in effect, Saddam's "royal guard" and his main defense against a revolt by the army. The other 150,000 troops were mainly Sunni and Shia draftees, although there were Kurd and other minorities (Turks, and several Christian groups). At the time of the 2003 invasion, about 100,000 reservists (men who had done their conscript service recently) had been recalled to active duty. There were another 600,000 or so reservists who could have been called up. But many of these were Shia Arabs, and Saddam didn't want to see lots of armed Shia, in uniform or not. Still, the army, when fully mobilized, amounted to some 900,000 armed men.
The major difference between the 2010 Iraqi army and Saddams force was training. The only troops Saddam allowed to get much training was the Republican Guard. The Shia Arab and Kurdish troops had fought for Saddam in the 1980s war with Iran, but quickly deserted when confronted by Coalition (mainly U.S.) troops in Kuwait in 1991. Same thing happened during the 2003 invasion. Some Republican Guard forces put up a fight, but most of the army fled. Saddam's army was a weak combat force, and even the Republican Guard was quickly broken. Note that the Iraqi army had a long history of shabby performance.
The core of Saddams armed forces were his secret police, intelligence and paramilitary organizations. All these amounted to about 100,000 armed men. Many were basically thugs in civilian clothes. But they could be depended on, because they were Sunni Arabs. Less reliable were the 100,000 or so national police and border guards. These could be bribed, although in wealthier areas, the cops received additional payments from local civilians, and maintained law and order.
In effect, Saddam built a reliable force of 200,000 Sunni Arab troops and secret police (from a total Sunni Arab population of five million). That was four percent of all Sunni Arabs, whose main job was not fighting foreign invaders, but keeping the other 80 percent of the population under control. Counting reserve officers and NCOs who also received payments, and the majority of civil service jobs that were reserved for Sunni Arabs, you can see how important Saddam was to Iraqi Sunni Arabs. Saddam provided jobs, or some regular income, for about half of all adult Sunni Arab males. These guys were not particularly well trained fighters, but they were loyal. Many were willing to fight for years in an effort to regain the good old days.
The current army has been much more carefully selected and trained. Most of the troops, especially the officers and NCOs, are Shia Arabs, with a large Kurdish minority. Many of these had never served as officers and had to be trained from scratch. This takes a long time, and there were still shortages of experienced staff officers (who outnumber commanders of units) Many of the 20,000 Sunni Arab officers did find employment, if not much love, in the armed forces.
Since 2011 the Shia politicians running the government chose politically reliable Shia officers over those who were merely competent at their jobs. That led to the collapse of the Iraqi army in the face of a mid-2014 Sunni terrorist offensive. That should not have happened, but it did and will again unless the Iraqis put more emphasis on competence than political loyalty when selecting military officers.