US can attack Iran sites 200 feet underground

Washington Post:

Western spy agencies for years have kept watch on a craggy peak in northwest Iran that houses of one the world’s most unusual nuclear sites. Known as Fordow, the facility is built into mountain bunkers designed to withstand aerial attack. Iran’s civil-defense chief has declared the site “impregnable.” 

But impregnable it is not, say U.S. military planners who are increasingly confident of their ability to deliver a serious blow against Fordow, should the president ever order an attack.
U.S. 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 remains far more vulnerable than generally portrayed, said current and former military and intelligence analysts. Massive new “bunker buster” munitions recently added to the U.S. arsenal would not necessarily have to penetrate the deepest bunkers to cause irreparable damage to infrastructure as well as highly sensitive nuclear equipment, likely setting back Iran’s program by years, officials said. 

The weapons’ capabilities are likely to factor in discussions with a stream of Israelis leaders arriving in Washington over the next week. The Obama administration will seek to assure the visitors, including Defense Minister Ehud Barak and Prime Minister Benjamin Netanyahu, of U.S. resolve to stop Iran if it decides to build a nuclear bomb. White House officials are worried that Israel may launch a preemptive strike against Iran with little or no warning, a move U.S. officials argue would be do little to stop Iran’s nuclear ambitions and may in fact deepen Iran’s determination to become a nuclear state. 

In arguing their case, U.S. officials acknowledged some uncertainty over whether even the Pentagon’s newest “bunker-buster” weapon — called the Massive Ordnance Penetrator, or MOP — could pierce in a single blow the subterranean chambers where Iran is making enriched uranium. But they said a sustained U.S. attack over multiple days would probably render the plant unusable by collapsing tunnels and irreparably damaging both its highly sensitive centrifuge equipment and the miles of pipes, tubes and wires required to operate it. 

“Hardened facilities require multiple sorties,” said a former senior intelligence official who has studied the formerly secret Fordow site and agreed to discuss sensitive details of U.S. strike capabilities on the condition of anonymity. “The question is, how many turns do you get at the apple?” 

U.S. confidence has been reinforced by training exercises in which bombers assaulted similar targets in deeply buried bunkers and mountain tunnels, the officials and experts said. 

U.S. officials have raised the necessity of multiple strikes as they warn Israel against a unilateral strike against Iran’s nuclear installations, the officials said. While Israel is capable of launching its own bunker-buster bombs against Fordow, it lacks both the United States’ more advanced munitions and the capability of waging a sustained bombing campaign over days and weeks, U.S. officials and analysts said.

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One of the weaknesses of an Israeli strike is their inability to sustain the strikes over the period of time needed to destroy the operations in a large country like Iran.  They would also need to take out other Iranian assets first in order to sustain operations.  Israel has always been the master of the one off strike, but they will probably need more than one in this case.  Iran may help Israel by lashing out at the US and its allies in the region giving them the incentive to finish the job.