Some say two years, others say four years. U.S. intelligence splits the difference.

Average it out and we’re staring at a full-blown, white-knuckle Middle East meltdown circa late 2009. If the IAF chooses to wait that long.

CBS News has learned that a new intelligence report says Iran has overcome technical difficulties in enriching uranium and could have enough bomb-grade material for a single nuclear weapon in less than three years.

U.S. intelligence officials caution that before Iran could meet or beat that 2010 date, it would have to make further technical progress in operating a uranium enrichment plant now under construction, reports CBS News national security correspondent David Martin.

As a result, there is no change in the official estimate that it will take Iran until 2015 to become a nuclear power. But David Albright, a leading expert, thinks that doesn’t give Iranian scientists enough credit…

Israel is the country most threatened by the prospect of an Iranian nuclear weapon. Former CIA officer Bruce Riedel says this latest intelligence would increase the chances of an Israeli strike launched with American-built warplanes.

“The Israelis have long believed that Iran is closer than U.S. intelligence believes it is,” Riedel says. “If they now hear that the Americans think it’s getting closer as well, it puts pressure on Israel to take its own action.”

Iran has 1,300+ centrifuges installed right now, which is enough to produce a bomb in 23-29 months — roughly the period that would take us to 2010 — if the centrifuges are being operated correctly. They’re planning to install another 1,700 within the next few months, though; assuming they’re not blowing smoke about having them and that they can operate those correctly, too, they can enrich enough uranium for a bomb within 8-10 months. The U.S. intel estimate must be based on the theory that Iran won’t figure out how to work the centrifuges until 2009 or so, when they’ll rev up all 3,000 and start churning out HEU in earnest. Otherwise the three-year timeline makes no sense.