The Soviet Union was restrained by the principle of mutual deterrence. The ruler of Iran wants, as his stated intention, to start a world war to bring in the 12th Imam or Mahdi.
A nuke in his hands, given the missile range of Iran's weapons could hit our troops in Iraq and Afghanistan, also Israel, southern Europe and with a little extra power, Moscow, and China.
True he could not hit the USA in North America directly. He could, however, send a suicide mission on a container ship into a harbor.
Obama is a nut case, as is the article.