"It's roughly about a year right now. A little more than a year. And so… we think we will have the opportunity once we know that they've made that decision, take the action necessary to stop (Iran)," Panetta said on CBS' "This Morning" program.
- Can Israel still surprise Iran?
- US on Iran: There is still time for diplomacy
- Iran threats help Bibi, Barak
He said the United States has "pretty good intelligence" on Iran. "We know generally what they're up to. And so we keep a close track on them."
Panetta said the United States has the capability to prevent Iran from building an atomic bomb.
"We have the forces in place to be able to not only defend ourselves, but to do what we have to do to try to stop them from developing nuclear weapons," he said.
The United States and Israel believe Iran is working toward developing nuclear weapon development capability. Israel, widely thought to be the Middle East's only atomic power, says a nuclear-armed Iran would be a threat to its existence.
Iran says its nuclear work is for peaceful energy purposes only.
Israeli Prime Minister Benjamin Netanyahu on Tuesday ramped up threats to attack Iran, saying if world powers refused to set a red line for Tehran's nuclear program, they could not demand that Israel hold its fire.
Iranian President Mahmoud Ahmadinejad (Photo: AFP)
"The world tells Israel 'wait, there's still time.' And I say, 'Wait for what? Wait until when?' Those in the international community who refuse to put red lines before Iran don't have a moral right to place a red light before Israel," Netanyahu told reporters in Israel.
Netanyahu has said Israel and the United States were in talks on setting a "clear red line" for Iran's nuclear program. But the two allies remain at odds over whether to spell out a clear threshold for military action.
Powers voice 'serious concern'
Meanwhile, the six world powers voiced "serious concern" about Iran's uranium enrichment program and to urge Tehran to provide the UN nuclear watchdog with access to the sites it needs for its investigation, diplomats said on Tuesday.
They said the powers - the United States, Russia, China, France, Britain and Germany – had agreed a draft text on Iran's nuclear program at a meeting of the 35-nation governing board of the International Atomic Energy Agency (IAEA) in Vienna.
If the text becomes a resolution with broader support, that would be welcomed by Western diplomats, who have been pressing for such a move to add to international pressure on Iran over atomic activities they suspect is aimed at developing nuclear bombs. Tehran says the work is peaceful.
The fact that the six powers were able to agree a joint text underlined their desire to maintain unity over the long-running dispute, which has the potential to plunge the Middle East into a new war.
China and Russia have backed a series of UN Security Council sanctions rounds imposed on Iran since 2006.
- Receive Ynetnews updates
directly to your desktop