Actually according the the liberals precious IAEA we have good evidence they are, and none they they want nuclear material for peaceful research and medicine as they claim.
Further, Iran has stated repeatedly that Israel has no right to exist, while Israel has never stated that ANY country doesn't have the right to exist. On top of that Iran has publicly stated that they would like to use nukes to "destroy the Zionists and push Israel into the sea". I'd call that pretty freaking militant language myself.
Iran scared? Are you nuts? The Mullahs that run Iran believe that if they die the go to paradise, they have no reason to be scared. Also if they're scared why are they being so prickly about the issue? Why not just capitulate? If Israel got aggressive for no reason the whole WORLD would be out to stop them.
Iran isn't scared, they want to be the hegemony in the Middle East. Almost every other country in the region (with the notable exception of Syria) is scared of them.
Sanctions with a HARD bite are needed. If that doesn't happen there are very few outcomes possible. 1) Iran gets a bomb and ignites a nuclear weapons race in the Middle East. 2) Israel attacks their nuclear sites before they can build a bomb, potentially starting WWIII with conventional weapons. 3) The weapons race in the Middle East leads to WWIII. 4) Iran drops a nuke on Israel, starting WWIII.
What you fail to understand is that Iraq, Saudi Arabia, Jordan, Egypt, Qatar, Oman, Yemen, the UAE and Lebanon all have a history of Iran meddling in their internal affairs in the last 30-40 years, usually supporting anti-government and anti-Israeli groups or both. They hate Iran and fear them, in most cases more than they hate Israel.