Western intelligence experts believe that Iran's nuclear facilities are so deep underground that it would be difficult for Israel to wipe them out, or even significantly damage them, with a quick airstrike. In order to deal a serious setback to Iran's nuclear program, at least four key sites inside Iran would have to be hit, said one Western official, who asked for anonymity when discussing sensitive information. The facilities, however, are located in tunnels fortified by barriers more than 60 feet thick. According to this official and other U.S. experts, Israel does not possess conventional weapons capable of knocking out the facilities. Breaking through the thick shell would require, at minimum, several bunker-buster bombs striking precisely the same spot. "These targets would be very hard to destroy," said former U.N. nuclear expert David Albright. Theoretically, Israel could do a lot more damage with a nuclear strike. But U.S. and other Western experts say there is no reason to believe the Israelis will abandon their policy against shooting first with nukes.
U.S. and allied efforts to keep tabs on Iranian nukes suffered a blow recently because of a "spy vs. spy" mixup in Germany. For more than 10 years, according to two Western counterproliferation officials, the BND (Germany's equivalent of the CIA) employed an Iranian-Canadian informant known by the code name "Sinbad." Sinbad peddled technology to the Iranians, and, in turn, brought the BND high-quality Iranian government documents, including what Germany's Der Spiegel magazine described as pictures of tunnel-digging machinery and briefing papers on nuclear delivery systems. But the espionage operation recently ran aground when German Customs officers, unaware of Sinbad's role as a spy, busted him for illegal missile-technology shipments to Iran. Sinbad had concealed extracurricular schemes from the BND, and the spy agency had no power to stop the investigation. One of the counterproliferation officials said that Sinbad's arrest was a significant setback to espionage efforts against Iran's nuclear program.