Given the nuclear weapon systems capability of the US, Russia, Israel, Pakistan, India, N. Korea, some European countries, etc. It is highly likely that no country will ever attack another with a nuclear weapon. It really does not matter if Iran produces a nuclear weapon. The real downside is that Iran will feel free to provoke Israel to a small extent feeling comfortable that Isreal will not use its nuclear weapons on Iran. In the end the US and Russia have so much capability that nuclear weapons would never be used by anyone openly. Terrorists can acquire nuclear weapons and that is the real danger.
Army: Blast in Korean DMZ wounds two South Korean soldiers (Reuters)