In Iran today, the head of the International Atomic Energy Agency said he is confident he can get Iran to suspend its nuclear program through sanctions.
But Iranian President Mahmoud Ahmadinejad's response wasn't so encouraging. "Our answer to those who are angry about Iran achieving the full nuclear fuel cycle is just one phrase. We say: Be angry at us and die of this anger," he said.
The international inspectors are in Iran to verify claims that the country has enriched uranium. But Nicholas Burns, undersecretary of policy at the State Department, said he doesn't need to wait for verification.
"We have no reason to doubt what happened this week," Burns said.
Another senior U.S. official said that is what makes the situation so dangerous.
"It is a very big deal," the official said. "We fear they could try to move quickly to a nuclear weapon."
Right now the Iranians said they have a working cascade of 164 centrifuges -- the machines that turn uranium into nuclear fuel. They have said they will now move to large-scale uranium enrichment.
Experts said that to have enough fuel to produce a bomb, you would need thousands of centrifuges, not just hundreds. So how long would it take for Iran to get there?
"Their plan would be to expand that centrifuge line to first a couple of thousand. And if they've got a two- to 3,000-cascade of centrifuges, they could make enough stuff for a couple of bombs a year," said Graham Allison, for assistant secretary of defense.
And how easy would it be to produce thousands of centrifuges?
"If they really worked flat-out, maybe in a couple of years they'll have 1,500 centrifuges," said Gary Sick, former member of the National Security Council who's now a professor at Columbia University.
Sick said he believes it would take Iran five years to develop a bomb. But a senior U.S. official worries that with the technology announced this week, a bomb could be ready in three years.