An excellent point made in the Wall Street Journal today:

It's also important to consider the effect that a nuclear Iran would have on the potential for a democratic Iran. Its nuclear project is often portrayed as a matter of national prestige, the implication being that any strike against it would rally the regime's domestic opponents to its side. What Iranian dissidents tell us is closer to the opposite. A nuclear Iran would enhance the mullahs' sense of invulnerability and facilitate domestic repression.