A fire last week at Iran’s Natanz nuclear facility has caused “significant damage” and set back the country’s nuclear development program, according to government officials. Iranian security officials say they have uncovered the cause of the fire, but have yet to release further details. The New York Times cited a Middle Eastern intelligence official who says the site was destroyed by a bomb planted by Israel. The fire at the uranium enrichment facility is the latest in a string of fires and explosions in Iran, including a major blast at a military complex last month and an explosion at a medical clinic in Tehran one week ago, which killed 19 people and was attributed to a gas leak.