Maybe Obama’s invitation got lost in the mail? Iran’s leaders have invited several countries, including Russia, China, and the European Union, to take a tour of its nuclear facilities—but snubbed the U.S. The opportunity, just before more international talks on Iran’s nuclear ambitions, is suspected to be a ploy to gain support from the invited nations. The U.S. has been vocal about its concern that the country’s goal is to make nuclear weapons, but Iran insists that it is enriching uranium solely to generate nuclear energy. Diplomats last visited the nuclear sites three years ago, and could not determine the facilities’ aims at the time.