Just after midnight on 30 June, an email dropped into my inbox. It claimed to be from an unknown group calling itself the Homeland Cheetahs. The group said it had attacked the major Iranian nuclear site at Natanz some two hours earlier, at 02:00 local time. In the detailed message, it claimed it had blown up a facility and that the Iranian regime would not be able to hide it. The group said it was composed of dissidents within Iran's military and security forces and that they had been behind numerous attacks that the Iranian authorities had so far concealed from the public. I went online to check Iranian news agencies and reliable accounts on social media, but I found no mention of such an attack anywhere. Several hours later, Iran's Atomic Energy Organisation announced there had been an incident at the Natanz nuclear plant, but they ruled out sabotage. The next day, Iran's Supreme National Security Council - its top security body - announced that it knew what caused the "incident" at Natanz but that "for security reasons" it would not for the time being say what this was. Nasa satellite images showed there had been a fire at Natanz at 02:06. The damage corresponded with details contained in the email from the Homeland Cheetahs. The group's message had been carefully crafted and included a propaganda video about attacks on strategic sites it said it had carried out inside Iran. Preparing this kind of statement and video requires hours, if not days, of planning. Whoever authored it knew about the Natanz explosion in advance, which supports the theory that it was an act of sabotage. But there is also the possibility that the email was an elaborate attempt to mislead us as to who was behind the attack, and could actually be the work of foreign agents posing as opponents of the regime in Iran.