I'll go with the latter of your two theories. My problem with them blowing up underground tunnels is that trillions of dollars would be wasted.. cut in the white hats just take them over instead of destroying them? Couldn't they be used for future catastrophic events? Missile strikes? Shelters? I once read an article that said you could travel from coast to coast without ever coming above the surface of ground. Seems it would be more beneficial to expose any evil going on and preserve them for other uses.IDK