Israel has just carried out a major aerial exercise, putting a hundred or so F-15s and F-16s into the skies over the eastern Mediterranean, evidently a rehearsal for a strike against Iran’s nuclear facilities. The move follows the statement earlier this month by Shaul Mofaz, Israel’s deputy prime minister, that an Israeli attack on Iran’s nuclear program is “unavoidable.” Israel almost certainly knows the location of some of the critical nodes in the Iranian program that it must hit if it is to set the Iranian effort back by several years. It also possesses the technology to assure that its bombs will fall close to or on their targets. But would such a strike succeed?
We cannot know the answer, and neither can the Israelis. The question calls attention to what might be called the ongoing Counterrevolution in Military Affairs.
The Revolution in Military Affairs was based upon silicon, in particular the computer chips that make for precision-guided weapons. In the 1980s, the United States developed the technology to drop munitions near enough to their targets to ensure a high chance of destruction. In World War II, the circular error probable–the radius of a circle into which a projectile will land at least 50 percent of the time–was more than half a mile. Today, thanks to GPS systems and laser- and infrared-guiding devices, the radius is less than two dozen feet. Almost any given target can be knocked out by the use of just one or two conventional bombs.
In the face of the threat of such efficient destruction, Iran has not stood still. Some of its countermeasures are themselves based upon computerized systems, including highly effective Russian-made surface-to-air missiles that Iran is set to take delivery of this fall. But Iran is also employing a far older means of warfare: deep burrowing.
More typical, though, is defensive digging. In Berlin, beneath an otherwise unremarkable Chinese restaurant, are the ruins of the most notorious underground facility in history: the Führer bunker. Adolf Hitler held court here in the last phase of World War II, and it was in the bunker that, on April 30, 1945, together with his new bride, he ingested cyanide. As an engineering feat, the Führer bunker was not particularly impressive; Hitler’s honeymoon grave was a mere 28 feet underground.
At the dawn of the nuclear age, the USSR constructed a vast network of tunnels under Moscow, including a 17-mile secret subway line to Vnukovo airport, to ensure that the leaders of the Kremlin would survive a nuclear strike. Some of these underground facilities were hundreds of yards deep and could accommodate thousands of people, sustaining them in compartments impervious to chemical and biological attack. It required a totalitarian system to marshal the manpower and resources to remove such an immense quantity of soil and rock.
Today, however, tunneling is far cheaper and easier. In the early 1990s, the Chunnel, the 30-mile rail tunnel connecting France and England, was built using drilling machines that hewed out a 30-foot diameter circle of rock at the remarkable pace of 164 feet a day. Modern drills are huge, multi-million-dollar pieces of machinery. They operate with a circular disk on the front end that holds steel teeth, which cut into the rock as the plate rotates. A conveyor system pulls the spoil backward, while workers follow up, erecting a reinforced lining for the excavated structure. Narrower diameter tunnels than the Chunnel can be carved into solid rock at the staggering rate of 650 feet per day.
The military significance of all this cannot be overemphasized: Ultra-deep shelters for critical military facilities can be made formidably resistant to attack. It is exceedingly difficult to discern from the surface where tunnel ventilation shafts are located or in which direction a tunnel proceeds. One has only to consider the trouble Israel has had finding tunnels dug by Hamas out of the Gaza Strip that are just a couple of yards below the surface. Another difficulty is determining exactly what military activities are being conducted in any given tunnel.
What is more, if tunnels are dug to a sufficient depth in the right kind of rock–a thousand or more feet into the earth–they are extraordinarily difficult to breach. Even a medium-yield nuclear weapon detonated above ground may not be powerful enough to do the job. Reportedly acting with help from North Korea (and as Emanuele Ottolenghi notes in the July-August Commentary, employing imported European machinery), Iran has built dozens of underground bunkers to house its missile and nuclear programs.
The United States (and presumably Israel) is urgently developing ways to neutralize such targets. Concepts range the gamut from munitions that deliver a powerful shock into the adjoining bedrock to nonlethal methods for introducing a foul odor into the underground chambers, rendering human habitation unbearable.
The problems posed by tunneling seldom come in for public discussion. This happened most recently in 2005 when Congress shelved a Bush administration plan merely to study development of something called the Robust Nuclear Earth Penetrator (RNEP), amid talk it would ignite an arms race. RNEP was a weapon that would have served as a deterrent to any regime thinking it could buy invulnerability by digging deep. Its defeat was ironic because only a few years earlier, without a peep from Congress, the Clinton administration pushed through the innocuously named B61-11 bomb, which had strikingly similar characteristics, though it tends to break apart when boring into certain types of geological formations in which a hardened target might be located.
Whatever the fate of the RNEP, nuclear weapons were never the best answer to the tunneling problem given the prohibitive political costs of ever employing them. More practical would be the Massive Ordnance Penetrator, a 30,000-pound package under development jointly by Boeing and Northrop Grumman that is the largest conventional bomb ever built. Precision guided like everything else these days, it would be the ideal weapon to rattle–and perhaps pulverize–a target like Iran’s underground uranium-enrichment facility at Natanz.
In one of his recent outbursts, Iran’s president, Mahmoud Ahmadinejad, called Israel a “stinking corpse,” destined to disappear. Such outrageous language coming–not for the first time–from the head of a state seeking nuclear weapons, has made the Iranian nuclear program all the more ominous. The day is clearly growing closer when the West is going to either face the challenge or, if it permits the ayatollahs to acquire nuclear weapons, suffer a strategic setback with a range of predictable and unpredictable consequences. The Massive Ordnance Penetrator, still in the testing phase, cannot be fitted to the bays of American bombers a day too soon.
Gabriel Schoenfeld is the senior editor of Commentary.