The Mossad agents moving in on a warehouse in a drab commercial district of Tehran knew exactly how much time they had to disable the alarms, break through two doors, cut through dozens of giant safes and get out of the city with a half-ton of secret materials: six hours and 29 minutes.

The morning shift of Iranian guards would arrive around 7 a.m., a year of surveillance of the warehouse by the Israeli spy agency had revealed, and the agents were under orders to leave before 5 a.m. to have enough time to escape. Once the Iranian custodians arrived, it would be instantly clear that someone had stolen much of the country’s clandestine nuclear archive, documenting years of work on atomic weapons, warhead designs and production plans.

The agents arrived that night, Jan. 31, with torches that burned at least 3,600 degrees, hot enough, as they knew from intelligence collected during the planning of the operation, to cut through the 32 Iranian-made safes. But they left many untouched, going first for the ones containing the black binders, which contained the most critical designs. When time was up, they fled for the border, hauling some 50,000 pages and 163 compact discs of memos, videos and plans.