I suspect you don't really believe what you're saying, Bart. You can't penetrate rock with multispectral imagery.
Russ,
To even dig a tunnel in rock or underground, ground has to be moved, seismic activity may be recorded, trucks have to transport equipment, electricity must be generated by equipment, ventilation is required, personnel has to travel and drink and eat, etc., etc.
And all that activity will produce CO2, which can be measured, and money needs to be paid to purchase materials.
It's not easy to do something that will not be noticed, especially when watched so closely.
But now, it doesn't matter anymore, since there is no longer a deal, and Iran refuses to talk with the USA until the sanctions are lifted.
Cheers,
Bart