Displaced Sunni Iraqis, who fled the violence in Ramadi, arrive at a makeshift camp on the outskirts of Baghdad, in April. Ahmad Al-Rubaye/AFP/Getty Images hide caption

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Shiite fighters and Sunni fighters, who have joined Shiite militia groups known collectively as Hashid Shaabi ("Popular Mobilization") to fight the Islamic State, gesture Tuesday next to former Iraqi President Saddam Hussein's palaces in the Iraqi town of Ouja, near Tikrit. Thaier Al-Sudani/Reuters/Landov hide caption

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Mourners carry the coffin of a victim of a bomb attack on a Baghdad cafe on Tuesday. Violence in Iraq has spiked this year. The bodies of 18 men were found Friday in a Sunni area near Baghdad. Sabah Arar/AFP/Getty Images hide caption

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Pakistanis check the site of a bomb blast in Karachi on Sunday. Pakistani officials say the blast has killed dozens of people in a neighborhood dominated by Shiites. Fareed Khan/AP hide caption

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A fresco painting from the Chehel Sotun Pavillion in Isfahan, Iran, depicts Persian warfare during the Safavid dynasty period. Dave Bartruff/Corbis hide caption

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