Defense and intelligence officials told the Post that they're aware of the activity, but refused to comment further. The paper was alerted to the Natanz project by the Institute for Science and International Security (ISIS), which detected the apparent tunneling through commercial satellite photos of the area.
David Albright, the head of the ISIS (and a former U.N. weapons inspector) said that the new effort appears similar to a tunnel project at the Esfahan nuclear facility, located about 80 miles south of Natanz. Photos taken by the Digital Globe satellite in mid-June showed construction of two roads from the Natanz facility, to the side of a mountain closest to its southern perimeter. According to Mr. Albright, tunnel entrances are not visible in the images, although piles of rock and debris--known as "spoil" in the imagery interpretation business--can be seen, suggesting that tunneling is underway. No construction was visible in satellite images of the area taken six months ago.
Similar activity was observed at Esfahan in 2004, where Iran built a large, U-shaped tunnel near its uranium conversion facility. Material produced at Esfahan is shipped to Natanz, where it is processed into fuel that can be used in a nuclear reactor or a bomb, depending on its purity. Available information suggests that the centrifuges at Natanz have not reached sufficient purity levels for nuclear weapons, although continued enrichment of existing material could eventually yield bomb-grade uranium.
Mr. Albright believes that storage is the most likely function for the Natanz tunnel complex, given the recent construction of hardened, underground facilities believed to house the centrifuge array. The tunnels could be used to protect critical equipment--and personnel--from air attack. The absence of tunnel entrances on the Digital Globe imagery suggests that Tehran selected the location with great care--and with an eye toward complicating detection from overhead reconnaissance platforms.
We've seen similar techniques in other countries--notably Pakistan--with advanced nuclear and denial and deception (D&D) programs. Imagery analysts tell us that some of Islamabad's nuclear tunnels are extremely difficult to detect, because the Paks make a concerted effort to "blend" the entrances into surrounding terrain. While the inability to locate tunnel entrances on the Digital Globe photos may simply be the result of shadows or a poor "graze" angle, it could also suggest a growing sophistication in Tehran's nuclear D&D efforts.
And, take that "storage" mission with a grain of salt. Inspectors from the International Atomic Energy Agency (IAEA) eventually gained access to the Esfahan tunnel, and determined it was too large to simply support a storage function. If the Natanz project is of similar scope--and Mr. Albright's analysis suggests that it is--then Iran may have other functions in mind, including a division of enrichment efforts between the underground facilities and the tunnel. That would complicate targeting for an adversary with limited strike assets (i.e. Israel). Other possible uses for the tunnel include the storage of nuclear weapons (if Iran reaches that milestone), or as an underground base for ballistic missiles.
Iran has plenty of experience in tunneling. For years, the Iranian government has invested heavily in the purchase of drill jumbos and other tunnel construction equipment, often purchased from Sweden. While some of the equipment was used for "legitimate" purposes--including tunneling for Tehran's subway project--other assets were diverted for military projects. Iran also has access to experts from China, Pakistan and North Korea, who are highly skilled at the construction (and concealment) of tunnels.
While the IAEA claims that Iran has slowed expansion of the Natanz centrifuge array, the near-by tunnel project affirms that Tehran has big plans for the facility. Indeed, the current slowdown may be related to technical problems with the current centrifuges. Iranian scientists may be attempting to improve the efficiency of the array--and increase the purity of their enriched uranium--before increasing the number of centrifuges in operation. At this point there's virtually no chance that Iran will comply with the IAEA's request to "freeze" enrichment work at current levels, and the tunneling hints at a (potentially) massive effort in the near future.