True, Iran has supported terrorists like Hamas and Hezbollah, but generally the mullahs seem quite caredul and conservative in their approach to expanding Iranian influence. Notice that so far neither Hezbollah or Hamas have even used heavy rockets or artillery for instance. I don't think there's any chance whatsoever that Iran would give Hamas or Hezbollah a nuke to play with, even if Iran had any. It's the same way the the Soviet Union never gave nukes to any of the guerrilla organisations that it and its allies backed.
from the article: Lieberman: How will the world stop Iran if it can't stop N. Korea?