U.S. President Barack Obama talks about Iraq at White House in WashingtonBy means of Raheem Salman and Isabel Coles BAGHDAD/ARBIL Iraq (Reuters) – U.S. warplanes bombed Islamist fighters marching on Iraq's Kurdish capital on Friday after President Barack Obama stated Washington must act to prevent "genocide." Islamic State opponents, who’ve beheaded and crucified captives of their force to eradicate unbelievers, have developed to within a half hour's power of Arbil, capital of Iraq's Kurdish region and a hub for U.S. oil companies. Obama authorized the primary U.S. air strikes on Iraq given that he pulled all troops out in 2011, arguing motion was once needed to halt the Islamist strengthen, give protection to American citizens and defend lots of of thousands of Christians and individuals of other religious minorities who’ve fled for their lives.