BAGHDAD (AP) — Iraq’s Shiite clerical leadership Friday called on all Iraqis to defend their country from Sunni militants who have seized large swaths of territory, and a U.N. official expressed “extreme alarm” at reprisal killings in the offensive, citing reports of hundreds of dead and wounded.

U.S. President Barack Obama said he is weighing options for countering the insurgency, but warned Iraqi leaders that he would not take military action unless they moved to address the country’s political divisions.