1 Kt is one thousand tonnes of high explosive!

The biggest bunker buster of WW2 was the British Grand Slam which carried 4 tonnes of high explosive and could blow through 40 meters of ground or 4-7 meters of reinforced concrete.

The weapon the Americans are probably going to use is the  B61 Mod 11. The weapon has variable yields starting at 10 Kt (or maybe as low* as 0,3 Kt) and up to 340 Kt.

* Wow! Only 300 hundred tonnes of TNT equivalent! That's only 25 times as much as a MOAB! What a mini-nuke!

Peak oil is not an energy crisis. It is a liquid fuel crisis.