Secretary of State Hillary Clinton took square aim at Iran's nuclear ambitions today, bluntly warning Tehran that "Your pursuit is futile." Clinton’s statements mark a step back from her musings earlier this week about creating a “defense umbrella” to protect other Middle Eastern countries from a nuclear Iran, Politico reports. “We believe, as a matter of policy, it is unacceptable for Iran to have nuclear weapons,” Clinton said. (More Hillary Clinton stories.)