Tensions among Iraq's major Shiite factions erupted into violence Tuesday as Iraqi security forces launched a major crackdown against militiamen in the southern oil hub of Basra. The fighting, which Iraqi officials said killed at least 35 people and injured 100, was the most serious sign yet that a cease-fire -- credited with helping improve security nationwide -- may be unraveling as sections of the Shiite majority jockey for position ahead of provincial elections. Explosions and machine-gun fire rocked Basra, where rival political factions, their allied militias and criminal gangs are vying for control of oil exports that generate most of Iraq's government revenue.
