One of the military’s initial option plans, as presented to the White House by the Pentagon this winter, calls for the use of a bunker-buster tactical nuclear weapon, such as the B61-11, against underground nuclear sites. One target is Iran’s main centrifuge plant, at Natanz, nearly two hundred miles south of Tehran. Natanz, which is no longer under I.A.E.A. safeguards, reportedly has underground floor space to hold fifty thousand centrifuges, and laboratories and workspaces buried approximately seventy-five feet beneath the surface. That number of centrifuges could provide enough enriched uranium for about twenty nuclear warheads a year. (Iran has acknowledged that it initially kept the existence of its enrichment program hidden from I.A.E.A. inspectors, but claims that none of its current activity is barred by the Non-Proliferation Treaty.) The elimination of Natanz would be a major setback for Iran’s nuclear ambitions, but the conventional weapons in the American arsenal could not insure the destruction of facilities under seventy-five feet of earth and rock, especially if they are reinforced with concrete.
There is a Cold War precedent for targeting deep underground bunkers with nuclear weapons. In the early nineteen-eighties, the American intelligence community watched as the Soviet government began digging a huge underground complex outside Moscow. Analysts concluded that the underground facility was designed for “continuity of government”—for the political and military leadership to survive a nuclear war. (There are similar facilities, in Virginia and Pennsylvania, for the American leadership.) The Soviet facility still exists, and much of what the U.S. knows about it remains classified. “The ‘tell’ ”—the giveaway—“was the ventilator shafts, some of which were disguised,” the former senior intelligence official told me. At the time, he said, it was determined that “only nukes” could destroy the bunker. He added that some American intelligence analysts believe that the Russians helped the Iranians design their underground facility. “We see a similarity of design,” specifically in the ventilator shafts, he said.
A former high-level Defense Department official told me that, in his view, even limited bombing would allow the U.S. to “go in there and do enough damage to slow down the nuclear infrastructure—it’s feasible.” <snip>
But those who are familiar with the Soviet bunker, according to the former senior intelligence official, “say ‘No way.’ You’ve got to know what’s underneath—to know which ventilator feeds people, or diesel generators, or which are false. And there’s a lot that we don’t know.” The lack of reliable intelligence leaves military planners, given the goal of totally destroying the sites, little choice but to consider the use of tactical nuclear weapons. “Every other option, in the view of the nuclear weaponeers, would leave a gap,” the former senior intelligence official said. “ ‘Decisive’ is the key word of the Air Force’s planning. It’s a tough decision. But we made it in Japan.”
He went on, “Nuclear planners go through extensive training and learn the technical details of damage and fallout—we’re talking about mushroom clouds, radiation, mass casualties, and contamination over years. This is not an underground nuclear test, where all you see is the earth raised a little bit. These politicians don’t have a clue, and whenever anybody tries to get it out”—remove the nuclear option—“they’re shouted down.”