A plane crash that killed the head of the Iranian Revolutionary Guard's ground forces last week was most probably not caused by sabotage, leading Israeli analysts say. But it was the type of covert operation, they argue, in which Israel should be engaging as part of its efforts to delay or even possibly thwart Iran's nuclear program. "The only real way to operate [against Iran] is through covert operations," said Shabtai Shoval - a former member of the Israeli intelligence community and the author of a newly-released novel Ani Hanivhar (I, the Chosen) that deals with an Israeli prime minister informed that Iranian nuclear missiles are set to strike Tel Aviv. While Iranian officials blamed bad weather and dilapidated engines for last week's crash, there was room for speculation that foul play may have had a hand in the death of Brig.-Gen. Ahmad Kazemi and 10 other senior IRG officers. What was not reported at the time of his death is that Kazemi was responsible for the production and development of Iran's Shihab missiles, which are capable of delivering a nuclear warhead into the heart of Europe. Before that, Kazemi was active as an adviser to Hizbullah in southern Lebanon. Covert operations with similar results to last week's plane crash, Shoval insisted, were the only real way to delay Iran's nuclear plan. An air raid on Iran's nuclear facilities, he said, would ultimately fail since some of the reactors are hidden deep in underground bunkers. Therefore Israel had the best chance at thwarting the program by sabotaging one of the reactors and causing nuclear fallout, he said. "The goal is not to stop the plan since that is almost impossible," the former security official said. "We need to delay it by five years and hope that within that period the current Iranian government will be overturned." Former IDF deputy chief of staff Maj.-Gen. (res.) Uzi Dayan backed up Shoval's call on Israel to engage in covert operations but also hinted that the government needed to act "on a personal level" against Iranian President Mahmoud Ahmadinejad. "Israel needs to tell Ahmadinejad that he is held personally responsible for his actions," Dayan said. "He calls for the destruction of the State of Israel and he needs to know that his end will be like the end of Israel's former enemies." Dayan - who is running for the Knesset at the head of the Tafnit Party - called on the government to engage in operations that could not be traced back to Israel as it works to prevent Iran from achieving nuclear power. Kazemi is not the first Iranian rocket scientist to meet an unnatural demise. A few years ago, Col. Ali Mahmud Mimand, the godfather of the Shihab-3, was found dead at his desk. The Mossad was blamed, but Iranian insiders said he had been tortured to death by the Revolutionary Guard on suspicion of spying for the Americans or Israel. Covert options against enemy states' endeavors to get weapons of mass destruction are not alien to Israel. Mysterious bombings of equipment destined for Iraq's nuclear program and the assassinations of Iraqi nuclear scientists in Europe in the early 1980s were widely blamed on the Mossad. Last year, Iran accused the US and Israeli agents of tricking Iranian nuclear scientists abroad into giving away crucial information. "Israel needs to work to create a unified international bloc that will move the Iranian issue from diplomatic channels to real sanctions on Iran," Dayan said. "Israel also needs to take steps to thwart the plan with operations that it can deny. If all else fails, and there is no other alternative, then we should launch an overt strike." Not all analysts agree with Shoval and Dayan. Ephraim Kam - the deputy head of the Jaffee Center for Strategic Studies and an expert on Iran - called on Israel to stick solely to the diplomatic course and to refrain from engaging in any military action unless as a last resort. "Covert operations will not do anything," said Kam, who served as a colonel in the Research Division of IDF Military Intelligence until 1993. "These types of operations cannot stop the program. Sabotaging planes won't stop anything." Ultimately, most experts agreed that covert actions could only delay Iran's efforts to go nuclear but not kill off the plan. The sabotage and assassinations against the Iraqi efforts only slowed down Saddam Hussein but didn't deter him, they pointed out. In the end, Israel took the overt course, and bombed the Iraqi Osirak nuclear reactor in 1981.