Iranian nuclear scientist latest victim of covert sabotage efforts Iranian officials confirmed that Roshan had worked as a deputy director at Natanz, where uranium is being enriched in defiance of five United Nations resolutions. This highly sensitive process could be used to make the essential material for a nuclear weapon. Roshan was believed to be an expert in gas separation, an essential technology for enrichment. Iran's Atomic Energy Organisation gave a defiant response to his death, blaming America as well as Israel and promising to continue developing peaceful nuclear technology. "The heinous acts of American and the criminal Zionist regime will not disrupt our glorious path," said the statement. The more you kill us, the more our nation will become awakened. Mark Fitzpatrick, director of non-proliferation at the International Institute for Strategic Studies, noted that Egypt's attempt to acquire nuclear weapons capability in the 1970s was successfully derailed by the assassination of key figures. This enforced loss of expertise, widely attributed to Israel, had been "crucial in preventing Egypt from getting very far," said Mr Fitzpatrick. "Iran's programme is further advanced, so I don't know if a decapitation strategy would work," he added. But it's possible that this, in conjunction with other strategies - industrial sabotage and so-called 'accidental' explosions in sensitive facilities - is having some effect in retarding the Iranian programme. An explosion at a military base last November killed General Hassan Tehrani Moghaddam, head of Iran's ballistic missile programme. Meanwhile, the most effective covert action was probably the infection of the Natanz plant with the Stuxnet computer virus. This caused hundreds of uranium-enriching centrifuges to spin out of control and then blow up in 2010. Iran was briefly forced to halt all enrichment while emergency repairs were carried out. Morale among Iran's fraternity of nuclear scientists is believed to have suffered accordingly. Many live under the tightest security, notably Mohsen Fakrizadeh, a professor of physics and officer in the Revolutionary Guard Corps who is believed to occupy one of the most senior positions. The scientists are also the focus of intense security screening. The centrifuges at Natanz were not connected to the internet, so the Stuxnet virus must have been introduced by a human agent. Since then, Iran is believed to have tightened up what were lax security procedures.