The oppressive and vindictive rule of Iraqi Prime Minister Nouri al-Maliki, whose divisive governing has alienated and marginalized Sunnis and Kurds, has played a significant role in the deterioration of security and the emergence of Sunni extremists, experts on the troubled country say.

"I believe a great deal of the crisis can be laid at the feet of Nouri al-Maliki," said Peter Mansoor, the former executive officer to then general David Petraeus during the period of the Iraqi surge in 2007 and 2008. "Ever since the withdrawal of U.S. forces in 2011, he’s proven to be a highly divisive, extremely authoritarian and extremely sectarian figure.

"He’s governed Iraq with an iron fist, he has alienated large segments of the Iraqi population, including its Sunni and Kurdish inhabitants, and his governing style has led directly to this moment when he’s lost control of more of third of his country."

The al-Qaeda-inspired Islamic State in Iraq and Syria (ISIS) has overrun several Iraqi cities and posed the worst threat to the Shia-led government since U.S. troops left in 2011.

"I believe that had Nouri al-Maliki made a serious effort to reconcile with the Sunni community and Kurdish community and governed in a more even-handed manner, that the region wouldn’t be in this position today," said Mansoor, author of the book Surge: My Journey with General David Petraeus and the Remaking of the Iraq War.

"It says something when the Sunnis feel so bad about the way they’ve been treated that they would forge a temporary alliance with these very extremist jihadists."

Al-Maliki, the Shia leader of the Dawa Party, became prime minister in 2006, when he was initially seen as the compromise candidate, a somewhat weak leader who was acceptable to all factions, and possibly viewed as someone who could be controlled. 

'Ready to go after his political enemies'

Initially, during the so-called U.S surge in 2008 against al-Qaeda in Iraq, al-Maliki helped in the fight against the insurgency and was considered even-handed in going after Sunni and Shia extremists, Mansoor said.

"That turned out not to be the case in the long run," Mansoor said. "Once he thought he had won, then he was ready to go after his political enemies, and he viewed those enemies very much in a sectarian lens."

Instead of reaching out to other factions, al-Maliki began arresting Sunni citizens and key Sunni politicians, and putting them in jail without trial. Meanwhile, he packed the courts with his political cronies and further marginalized the Sunni community by not providing them with a fair share of budget resources, Mansoor said.

"So in just about every way you can imagine, he has alienated the Sunni community, and unfortunately what that has done, it has turned them against the government that they appeared to be on the verge of supporting after the success of the surge," Mansoor said.

And by undermining the reconciliation and reintegration of Sunni Arabs, in particular the Sunni militia known as the Awakening Council (Sons of Iraq) who fought with U.S. and Iraqi forces during the height of the insurgency, al-Maliki  has weakened Iraq's defence, said Derek Harvey, a former intelligence analyst for Iraq who served as a policy adviser to Petraeus. 

“A fairly stable situation was aggravated significantly by Prime Minister Maliki’s decision and reluctance to engage in a political process that would have been more inclusive," Harvey said. "And, in fact, he took apart what we had built up the previous year, brick by brick by brick."

Al-Maliki also began purging competent professional officers whom the U.S had spent years training and developing because they were not "party hacks," Harvey said, and were not family members or otherwise connected to the prime minister and the Dawa Party.

This meant the ability of the Iraqis to respond effectively to the recent developments in the north have been undermined by the lack of support from the Sons of Iraq, the incompetence of officers in charge and by having command and intelligence micromanaged by the prime minister's office, Harvey added.

"So commanders and staff and others had no battlefield awareness, and so they were stuck blind on these posts without good leaders," he said. "Are you going to fight for that, if you're a Shia soldier in Mosul or Tikrit, when you see the leaders abandoning or not competent?"

Harvey said this outcome was clearly predictable and blamed the Obama administration in part for not pushing to maintain a large U.S. force in Iraq that could keep the training and mentoring of the Iraqi military on track and continue to professionalize it.

But also, he said, "So we could be a check on the worst tendencies of Prime Minister Maliki and others."

With files from The Associated Press