Who knows what's really happening? But here's some speculation from the Miami Herald (datelined Jerusalem):
Iran explosions prompt speculation of secret attacks
JERUSALEM -- "A series of mishaps at Iranian nuclear facilities and weapons sites may be part of a covert organized attack on Iran's nuclear weapons program, according to Western intelligence officials.An explosion last week outside Iran's third largest city, Isfahan, is thought to be the most recent strike, though details on the intended target are still unclear. A sprawling military base and nuclear facilities are outside Isfahan, and intelligence officials across the Middle East said there was strong evidence that the explosion had done some "significant structural damage."
"We have seen enough evidence to know something has happened, but we are unclear on what at this point," said one Western diplomat whose work includes the region, speaking only on the condition of anonymity because of the sensitivity of the issue. "There are a number of parties interested in sabotaging and weakening the Iranian regime."
The second such incident in as many weeks cast doubt on Iranian claims that these were "accidents" and "coincidences," and it set off speculation of a coordinated attack by Israel, whose officials long have threatened a strike against Iran's nuclear program. Israeli officials denied direct involvement, but the growing number of mysterious or unexplained blasts and deaths has many suspecting an official program of sabotage." -more