Israel is making and supporting 4th generation war on Iran. It's using several of the tactics of such warfare. In addition to Stuxnet and the assassination of scientists, there is support for terrorists within Iran that are anti-government.
Power lines to Fordo were cut by explosives. I suspect Israel's hand in that. Iran reports that it discovered explosives planted in equipment it imports through a distributor from Siemans in Germany. Siemans denies planting explosives. I suspect Israel's hand in that too. Israeli agents could have reached the distributor or introduced explosives during the transportation. There is evidently a concerted and systematic campaign against anything Iran does related to nuclear energy. Yet another report is of a monitoring device camouflaged as a rock that blew up when moved. The British intelligence service MI6 is sometimes accused of being behind some of this.