Among the factors influencing a US or Israeli decision to attack Iranian nuclear and other facilities looks to be when (if?) a 1,000 MW reactor nearing completion at Bushehr is fully fuelled and goes critical sometime later this year. Or so I conclude from Iran: Consequences of a War by Paul Rogers.
If an attack really were thought to be imminent would the Iranians not already be moving key players and capacities into hidden and shadow facilities away from the obvious targets? Do they have the ability and resources to move fast enough?