The blast that rocked an Iranian missile base outside of Tehran may have been an accident, according to US intelligence.
The base was involved in testing solid fuel rockets - a volatile technology that Iran does not have much experience with. The massive explosion leveled the base and killed an important senior officer in charge of the program.
More probable than sabotage, one lucky accidental explosion may have set off a series of blasts that has set back Iranian missile development for perhaps years.
New York Times:
It is still unclear what caused the explosion, with American officials saying they believe it was probably an accident, perhaps because of Iran's inexperience with a volatile, dangerous technology. Iran declared it an accident, but subsequent discussions of the episode in the Iranian news media have referred to the chief of Iran's missile program as one of the "martyrs" killed in the huge explosion. Some Iranian officials have talked of sabotage, but it is unclear whether that is based on evidence or surmise after several years in which Iranian nuclear scientists have been assassinated on Tehran's streets, and a highly sophisticated computer worm has attacked its main uranium production facility.
Both American and Israeli officials, in discussing the explosion in recent days, showed little curiosity about its cause. "Anything that buys us time and delays the day when the Iranians might be able to mount a nuclear weapon on an accurate missile is a small victory," one Western intelligence official who has been deeply involved in countering the Iranian nuclear program said this weekend. "At this point, we'll take whatever we can get, however it happens."
In addition to providing a potential deterrent to attackers, Iran's advances in solid-fuel missile technology, and the concern it could eventually have intercontinental reach, have been at the heart of the Obama administration's insistence on the need for new missile-defense programs.
Evidently it was the size of the blast that has led American officials to surmise an accident rather than sabotage. Be that as it may, happy circumstance or deliberate destruction, the explosion was a godsend.