A fleet of nine U.S. military ships in the Persian Gulf as a show of force includes two nuclear-powered aircraft carriers, whose presence adds to the pressure on Iran to abandon its own nuclear ambitions which the West says are an attempt to develop atomic weapons. Iran, already under U.N. sanctions for enriching uranium, says its plans are for energy purposes only. Asked if any of the American ships carried atomic weapons, a U.S. navy spokesman said the United States routinely did not comment on whether its warships were equipped with nuclear arms. The ships, carrying about 17,000 personnel and 140 aircraft, will take part in war drills over the next two weeks, the group's leader Rear Admiral Kevin Quinn said, adding that the drills would include exercises to defend against air, surface and submarine threats. Quinn said the aim is to reassure allies of the U.S. commitment to regional stability. "We are conducting operations in support of our coalition troops on the ground in...