An Iraqi Turkmen fighter looks at an icon of seventh century Imam Ali bin Abi Talib, Islam's fourth caliph and cousin and son-in-law of Prophet Muhammad, in Taza Khormato, Iraq, earlier this month. Karim Sahib/AFP/Getty Images hide caption

itoggle caption Karim Sahib/AFP/Getty Images

The Iraqi prime minister's security spokesman, Lt. Gen. Qassem Atta, holds a press conference on Saturday in Baghdad. The government is launching an offensive against insurgents in the northern city of Tikrit. Ahmad al-Rubaye/AFP/Getty Images hide caption

itoggle caption Ahmad al-Rubaye/AFP/Getty Images

Joint Chiefs Chairman Gen. Martin Dempsey speaks during a news conference at the Pentagon in December. Manuel Balce Ceneta/AP hide caption

itoggle caption Manuel Balce Ceneta/AP

Fighters of the Islamic State of Iraq and Syria parade in a commandeered Iraqi security forces armored vehicle in Mosul, Iraq, on June 23. Human Rights Watch says the group executed at least 160 unarmed Iraqis after it took control of the city of Tikrit. AP hide caption

itoggle caption AP

A member of the Kurdish security forces stand guard atop a armored vehicle at Taza district, south of the oil-rich city of Kirkuk, Iraq, Friday, June 20, 2014. Emad Matti/AP hide caption

itoggle caption Emad Matti/AP

Iraqis who have fled as the Sunni extremist group ISIS has spread in northern Iraq enter a camp for displaced people between the Iraqi city of Mosul and the Kurdish city of Irbil on Thursday. Iraq's leader says he welcomes Syria's attacks on ISIS. Hussein Malla/AP hide caption

itoggle caption Hussein Malla/AP

Fighting between Iraqi government forces and the Islamic State of Iraq and Syria leaves buildings destroyed in Ramadi on Tuesday. AFP/Getty Images hide caption

itoggle caption AFP/Getty Images

The Islamic State of Iraq and Syria runs a sophisticated social media strategy, which includes images like this one it posted from Mosul, Iraq, on June 12 after it took control of the city. Analysts say ISIS has succeeded in bringing professional acumen to the business of violent jihad. AP hide caption

itoggle caption AP

Iraqi members of the Emergency Response Brigade patrol streets in the western city of Ramadi in Anbar province, where government forces are fighting extremist militants, including a force from the Islamic State of Iraq and Syria. -/AFP/Getty Images hide caption

itoggle caption -/AFP/Getty Images

Fighters from the Islamic State of Iraq and Syria march in Raqaa, Syria, in a picture posted on Jan. 14. The group is believed to hold as much as $2 billion. AP hide caption

itoggle caption AP

Mourners chant slogans against the al-Qaida breakaway group Islamic State of Iraq and Syria after they buried 15 bodies in the village of Taza Khormato in the northern oil-rich city of Kirkuk, Iraq on Monday. Emad Matti/AP hide caption

itoggle caption Emad Matti/AP