Republican presidential candidate Mitt Romney laid down a foreign policy marker on Wednesday, saying that if elected he would not allow Iran to develop nuclear weapons. An International Atomic Energy Agency report on Tuesday indicated Iran had worked to design nuclear bombs, testing Western powers anew in their standoff with Tehran, which insists it is developing a civilian nuclear program. Romney, leading some polls of Republican voters in the race to be the party's 2012 presidential nominee, said he would be prepared to work with U.S. allies on a diplomatic solution but would be prepared to act unilaterally if necessary...