The ticking clock of Iran's nuclear threat

Iran this weekend accused the CIA of masterminding the assassination of a nuclear scientist on the streets of Tehran this past Wednesday. The U.S. denies any involvement. Nevertheless, the clock is ticking in the Persian Gulf in what some fear could be a countdown to war. Our cover story is reported by national security correspondent David Martin:

The young Iranian nuclear scientist who was buried this weekend knew he was a target for assassination. He had a bodyguard. But they both were killed as they drove to work, by a motorcyclist who came alongside and clamped a magnetic bomb to their car.

Iranian nuke scientist killed by magnetic bomb

"This recent killing has got to be a blow to the Iranian government. That bodyguard didn't do his job, and the Iranian government didn't do their job to protect these scientists," said former weapons inspector David Albright, who keeps tabs on Iran's nuclear scientists.

"What difference do you think it makes now that he is no longer part of the Iranian nuclear program?" asked Martin.

"I hate to say it so crudely, but he's replaceable," replied Albright.

He said there is no one - as far as anyone can tell - who is irreplacable.

Except possibly for Mohsen Fakhrizadeh, a mysterious figure who is believed to head their nuclear weapons program but has never been seen in public.

"Certainly intelligence agencies that are interested in assassination would have a high interest in killing him," said Albright.

The CIA would no doubt like to see him dead, but it is barred by an executive order from conducting assassinations, like the one last week.

"We were not involved in any way, in any way, with regards to the assassination that took place there," said Defense Secretary Leon Panetta, who used to run the Central Intelligence Agency. "I'm not sure who was involved, we have some ideas as to who might be involved, but we don't know exactly who was involved.

"But I can tell you one thing: The United States was not involved in that kind of effort. That's not what the United States does."

You don't have to be a former CIA director to have the idea that Israel - which views Iran's nuclear program as a threat to its very existence - was involved in that and other assassinations of Iranian scientists.

Albright estimates there are hundreds of, professionals at the top level of Iran's nuclear program.

"So in the past two years, three have been killed," said Martin. "What kind of impact is that?"

"Doesn't have much direct impact, I would say," Albright said.

It certainly has not stopped Iran from enriching uranium to higher levels of purity by running it through centrifuges. But according to Dennis Ross, who until recently was the Obama administration's point man on Iran, the enrichment program is way behind schedule.

"By their own measure, they should have been at 50,000 centrifuges operating, and there are about 8,000 installed. So that's dramatically short of where they would have been," he said.

That's due in part to something called Stuxnet, a computer virus that someone - perhaps the U.S., perhaps Israel - infiltrated into the systems that run the centrifuges, causing them to spin out of control and self-destruct.

Albright believes the Stuxnet attack set back Iran's nuclear efforts by about a year.

But now Iran says it's opened a new uranium enrichment plant - dug deep into a mountain - that will allow it to step up production.

"By the end of this year they are going to have about 250 kilos of this 20 percent enriched uranium, which is a matter of concern for the international community," said Olli Heinonen, who used to inspect Iran's centrifuges for the International Atomic Energy Agency.

He says 20 percent enriched uranium is only one step away from bomb grade material: "Once you have 25 kilos of this material, in one month time you can produce uranium enough for a nuclear bomb."

Before that happens, the U.S. and its European allies intend to levy harsh sanctions on Iran that would put its central bank out of business.

"It's a big problem for Iran, because basically the central bank handles all the payments for their oil, so it is obviously a way to affect Iran's ability to sell their oil," said Ross.

On top of that, Europe - which buys about 18 percent of Iran's petroleum, a fifth of their oil revenue - is expected to ban imports of Iranian oil.

Iran's response has been to stage war games and threaten to close the Strait of Hormuz through which 15 million barrels of Mideast oil pass each day.

"For the Iranians to act on that threat they do themselves more harm than anybody else," said Ross.

Closing the Strait would cripple Iran's own oil exports and alienate virtually every nation which depends on Mideast oil, or cares about the price of oil.

"This wouldn't just be the United States that would have a concern about keeping it open," said Ross. "It would be the international community and it would be some of their most important trading partners, like China, for example."

Actually, the U.S. would be more than just "concerned" if Iran tried to close the Strait. Panetta said Iran blocking Hormuz would be a red line that America would not tolerate. Also a red line: Developing a nuclear weapon.

If it comes to that, the B-2 Stealth bomber has been outfitted with a 30,000-pound bunker-busting bomb designed to destroy Iran's underground nuclear facilities.

In an interview with Scott Pelley for "60 Minutes," Panetta warned Iran could cross the nuclear red line as early as this year.

"When the Secretary of Defense said a year, that's the worst case . . . the more likely case would probably be several years," said Ross.

That sounds like time enough for sanctions to decimate Iran's economy, and make the Ayatollahs think twice about how badly they want the Bomb.

There's one problem:

"The Israelis look at what time they have available still to them to use a military option if it was necessary," said Ross.

Israel's Defense Minister has warned Iran will soon have dispersed its nuclear facilities and hidden them underground to the point that a military strike could no longer stop the program.

"He's publicly giving interviews where he talks about 6 to 9 months from now," said Ross.

The red lines are fast approaching.

Assassination, sabotage and sanctions might delay them, but they will not be erased unless and until Iran gives up its nuclear ambitions.