TEHRAN, Iran - The United States is incapable of inflicting "serious damage" on Iran, President Mahmoud Ahmadinejad said Tuesday, as a second U.S. aircraft carrier group steamed toward the Gulf as a warning from Washington for Iran to back down in its attempts to dominate the region. In an interview with Iranian state television, Ahmadinejad said Washington had not stepped up its campaign against Tehran, despite the standoff with the West over Iran's defiance of U.N. demands to halt uranium enrichment. The U.N. Security Council imposed limited sanctions on Iran last month. "U.S. rhetoric against Iran has not increased," Ahmadinejad...