Iraq 's interim prime minister declared on Wednesday that the success of the national elections had dealt a major blow to the insurgents. But in a clear sign militants plan to continue their attacks, 12 Iraqi soldiers were killed in an ambush in northern Iraq. The Iraqi troops were returning to the northern city of Kirkuk, where they guard oil facilities, when armed men ambushed them Wednesday near the village of Zab, Maj. Gen. Anwar Mohammed Amin said Thursday. The ambush was the deadliest attack since Sunday's general elections. A U.S. Marine and two Iraqis who work on a U.S. military base were also killed in separate attacks.