Iran declines to disclose cause of fire

DUBAI, United Arab Emirates — An online video and messages purportedly claiming responsibility for a fire that analysts say damaged a centrifuge assembly plant at Iran’s underground Natanz nuclear site deepened the mystery Friday around the incident — even as Tehran insisted it knew the cause but would not make it public due to “security reasons.”

The multiple, different claims by a self-described group called the “Cheetahs of the Homeland” included language used by several exiled Iranian opposition organizations. They also focused almost entirely on Iran’s nuclear program, viewed by Israel as a danger to its very existence.

The disparate messages, as well as the fact that Iran experts have never heard of the group before, raised questions about whether Natanz again had faced sabotage by a foreign nation as it had during the Stuxnet computer virus outbreak believed to have been engineered by the U.S. and Israel. Tehran’s reaction so far shows Iranian officials are increasingly taking the possibility seriously.

“If it is proven that our country has been attacked by cyberattacks, we will respond,” warned Gen. Gholam Reza Jalali, the head of Iran’s military unit in charge of combating sabotage, according to a report late Thursday by the Mizan news agency.

Iranian officials have sought to downplay the fire, which erupted early on Thursday, calling it only an “incident” that affected an “industrial shed.” However, a released photo and video of the site broadcast by Iranian state television showed a two-story brick building with scorch marks and its roof apparently destroyed. Debris on the ground and a door that looked blown off its hinges suggested an explosion accompanied the blaze.