WASHINGTON/BRUSSELS (Reuters) - President Barack Obama said an announcement of six-power talks with Iran offered a diplomatic chance to defuse a crisis over its nuclear program and quiet the "drums of war." EU foreign policy chief Catherine Ashton, who represents the United States, Russia, China, France, Britain and Germany in dealings with Iran, announced Tuesday a fresh bid to allay suspicions that Iran is developing nuclear weapons after weeks of consultations with the other powers. ...