But then a huge explosion ripped through the Revolutionary Guard Corps base on Nov. 12, leveling most of the buildings. Government officials said 17 people were killed, including a founder of Iran's ballistic missile program, Gen. Hassan Tehrani Moghaddam.
Iranian officials called the blast an accident. Perhaps it was.
Decades of international sanctions have left Iran struggling to obtain technology and spare parts for military programs and commercial industries, leading in some cases to dangerous working conditions.
However, many former U.S. intelligence officials and Iran experts believe that the explosion — the most destructive of at least two dozen unexplained blasts in the last two years — was part of a covert effort by the U.S., Israel and others to disable Iran's nuclear and missile programs. The goal, the experts say, is to derail what those nations fear is Iran's quest for nuclear weapons capability and to stave off an Israeli or U.S. airstrike to eliminate or lessen the threat.