Not only does Israel have nuclear arms, they frequently launch incursions into Gaza and even Lebanon. Iran is right to fear for the territorial integrity of their nation and their allies, and they could use a nuclear deterrent. Finally, the United States, who have actually used nuclear weapons against civilians in the past, have recently overthrown the government of neighboring Iraq and are constantly meddling in the region. The United States also gave support to Iraq when Iraq attempted an invasion of Iran in the 80s. For Iran to feel secure and protect themselves, nuclear weapons are probably a good idea.