[Dr. Aaron Lerner - IMRA:

What's the danger if Iran has nuclear bombs?

"A nuclear-armed Iran could transform the landscape of the Middle East,
precipitating a nuclear arms race, dramatically increasing the prospect and
danger of local conflicts, fatally wounding the global non-proliferation
regime, and emboldening the terrorists and extremists who threaten the
United States and our allies."
National Security Advisor James L. Jones

So here is what National Security Advisor James L. Jones thinks the downside
is if Iran has nukes:

#1. Nuclear arms race - both on a regional and global level
#2. Local conflicts - apparently with conventional weapons.
#3. "Emboldening the terrorists and extremists"

What's missing from the list?

Yes.

Bottom line question: Does National Security Advisor James L. Jones
entertain the possibility that a nuclear-armed Iran might actually use a
nuclear weapon?

This is not an academic question.

When you weigh the costs of stopping Iran from getting the bomb against the
benefits, the cost-benefit equation is profoundly different if you think
that Iran might nuke someone.

If National Security Advisor James L. Jones and the rest of the decision
makers in Washington thought that Iran might nuke someone if they got the
bomb they would be willing to pay almost any price to make sure this didn't
happen

But they don't.

And, unfortunately, Iran knows this.