"They essentially delayed their arrival at the red line by eight months," said Ehud Barak, adding it was not clear why Iran stepped back.
Barak's time frame is in line with one Israeli Prime Minister Benjamin Netanyahu made in September when he spoke at the U.N. General Assembly. There, Netanyahu said the world has until next summer at the latest to stop Iran before it can build a nuclear bomb.
The West suspects Iran may be aiming toward production of nuclear weapons. Iran denies that, insisting that its program is for peaceful purposes.
Israel sees Iran's nuclear program as an existential threat, citing Iranian denials of the Holocaust, its calls for Israel's destruction, its development of missiles capable of striking the Jewish state and its support for anti-Israel militant groups.
Barak's comments, made during an interview late Thursday on Israeli Channel 2 TV, appeared to be based on an August report by the U.N.'s nuclear watchdog. It said that Iran has converted much of its higher-level enriched uranium into a powder for a medical research reactor that is difficult to reprocess for weapons production.
In the interview, Barak said Iran has not reached a "red line" on uranium enrichment, referring to Netanyahu's speech, where he explained that Israel could not tolerate waiting until Iran progressed most of the way to the uranium enrichment needed to make an atomic bomb.
The International Atomic Energy Agency report from August said Iran turned much of the uranium that was enriched to the higher, 20-percent levels into reactor fuel plates that are difficult to retool into warhead material.
As a result, it is still far short of the amount of more highly enriched uranium it would need to progress to weapons-grade levels.
"I don't know why they did it. I don't know if it was because of the deterrence that was connected to our statements and positions," Barak said. "Maybe it comes from other considerations but that allowed for the delay until the spring or summer."
Barak's statements contrasted with a report on the same TV station this week that said Israel was on the brink of an attack against Iran in the past. The report said that Netanyahu and Barak ordered the military to go on high alert for a looming attack on Iran's nuclear program two years ago. They backed off following strong objections from senior security officials, the report said.
The IAEA report also noted Iran has moved more of its uranium enrichment activities into fortified bunkers deep underground where they are impervious to air attack.
The international community has focused its efforts on diplomatic maneuvers to deter Iran from pursuing its nuclear program. U.S. lawmakers are working on a set of new and unprecedented sanctions that could prevent the Islamic republic from doing business with most of the world until it agrees to international constraints on its nuclear program.
Barak said Thursday he doubted that negotiations meant to persuade Iran to halt its nuclear program would be effective.
(Copyright 2012 by The Associated Press. All Rights Reserved.)