Western spy agencies for years have kept watch on a craggy peak in northwest Iran that houses one of the world's most unusual nuclear sites. Known as Fordow, the facility is built into mountain bunkers designed to withstand an aerial attack. Iran's civil defence chief has declared the site "impregnable."
But impregnable it is not, say US military planners, who are increasingly confident about their ability to deliver a serious blow against Fordow should the President ever order an attack.
US officials say they have no imminent plan to bombard the site, and they have cautioned that an American attack - or one by its closest Middle Eastern ally, Israel - risks devastating consequences such as soaring oil prices, Iranian retaliation and dramatically heightened tension in a fragile region.
Yet as a matter of physics, Fordow is far more vulnerable than generally portrayed, said current and former military and intelligence analysts.
Massive new "bunker buster" munitions recently added to the US arsenal would not necessarily have to penetrate the deepest bunkers to cause irreparable damage to infrastructure as well as highly sensitive nuclear equipment, probably setting back Iran's program by years, officials said.
The weapons' capabilities are likely to be a factor in discussions with a stream of Israeli leaders arriving in Washington over the next week. The US will seek to assure the visitors, including defense minister Ehud Barak and PM Benjamin Netanyahu, of US resolve to stop Iran if it decides to build a nuke bomb.
'How many turns do you get?'
US officials acknowledged some uncertainty over whether even the Pentagon's newest bunker-buster weapon - called the Massive Ordnance Penetrator - could pierce in a single blow the subterranean chambers where Iran is making enriched uranium.
But they said a sustained US attack over multiple days would probably render the plant unusable by collapsing tunnels and irreparably damaging both its highly sensitive centrifuge equipment.
"Hardened facilities require multiple sorties," said a former intelligence official.
"The question is, how many turns do you get at the apple?"
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