​Religious, political tensions hamper fight against ISIS in Iraq

Religious tensions complicate Iraq's war on I... 02:21

ISTANBUL, Turkey -- Iraqi Prime Minister Haider al-Abadi met with President Obama Tuesday to discuss Iraq's needs as it fights off the Islamic State in Iraq and Syria (ISIS). President Obama gave al-Abadi $200 million in humanitarian aid and credited him with making progress in pushing back ISIS.

Nearly 2,000 U.S.-led airstrikes have weakened ISIS in Iraq, leaving a trail of shattered buildings and incinerated vehicles.

New ISIS video purports to show destruction o... 01:45

According to the Pentagon, the strikes have helped win back more than a quarter of the territory that ISIS captured last year, including the city of Tikrit. But those victories are only half the story.

Iraq's army is so weak, corrupt, and disorganized, that the battle for Tikrit was led by Shiite Muslim militias -- armed volunteers with a history of torturing and killing Sunni Muslims. Some of the Shiite militias looted and burned houses in Tikrit. Others are accused of summary executions of Sunni Muslims, fueling Iraq's deadly religious tensions.

WASHINGTON - APRIL 14: U.S. President Barack Obama (R) listens as Iraqi Prime Minister Haider al-Abadi speaks after a bilateral meeting in the Oval Office of the White House April 14, 2015 in Washington, DC. The two reportedly talked about supporting the fight against ISIS, a strategic partnership and relations in commercial and cultural interests. Getty Images

Iraqi Prime Minister Haider al-Abadi came to power last year promising to unite his country. But in the fight against ISIS extremists he's done the opposite, relying on the Shiite militias and their backers in neighboring Iran.

"Iran is helping us and we say thank you to Iran, we say thank you to all countries who provide us with this support and this help," said al-Abadi.

Iranian military advisers in Iraq have stoked fears in the U.S. of Iran's rising influence in Iraq, especially as the Iraqis face their toughest challenge yet: retaking Mosul, a city of over a million people dominated by Sunni Muslims.

A Sunni Muslim militia is being trained to help lead the offensive on Mosul, but it's still small and poorly-equipped. The U.S. might not like fighting on the same side as Iran, but if it wants to defeat ISIS in Iraq, at this point, it doesn't have much choice.