[DuncanWaring]

Something tells me this isn't right. 200 feet of earth with some concrete hidden under it maybe.

Another suggestion is to drop two, a couple of seconds apart, programmed for the same target, so that the second one hits before the rubble from the first has collapsed back into the crater, for additional penetration.

[FreeAtlanta]

Why stop there? How about 4 or 5 of them? :-)