A simple thing is missing in this article. U.S, Russia, China and India are not Islamic nations. And Yes pakistan is islamic nation and still they don't give nuclear dirty bombs to terrorists, because they knew pakistan's taliban will explode the bomb both in New Delhi and Islamabhad. But Iran's case is different. First they don't have prominent Govt opposition terror organization. Second, they are not sunni muslims and they care least about themselves (even sunnis does the same. But to some extent they r ok.) Ayothulah once said, "We'll sacrifice Iran for Islam". These two main factors force them to give the worst weapons they have to Hezbullah and/or Hamas. And that's what israel is scared about.
Israeli vehicle hit in drive-by shooting in West Bank; no casualties reported (Haaretz)
from the article: Can Israel live with the Iranian bomb?