Backed by allied Shiite, Sunni and Iranian fighters, Iraqi security forces launched a large-scale military operation Monday to recapture Saddam Hussein's hometown from the Islamic State extremist group, a major step in a campaign to reclaim territory in northern Iraq controlled by the militants. Tikrit, the provincial capital of Salauhddin province, 130 kilometers (80 miles) north of Baghdad, fell to the Islamic State group last summer, along with the country's second-largest city of Mosul and other areas in the country's Sunni heartland.