It's my understanding that "bunker busters" are not nuclear weapons.
The Allied US and British military ( they were designed in the UK) has been testing them in Nevada, it appears that they have a small kiloton load (1-5) to prevent widespread radiation and that they have a device that will dig into the ground to seek the target and destroy it.
Thankfully the caves in Afghanistan didn't require the use of these weapons the Daisy Cutters did just fine.
I must have missed that part of the article, LOL...but if you think about it, a nuke COULD pretty effectively bust a bunker...or at least seal it in glass so thick whomever's inside had better have a few hundred pears worth of rations and air.
HEY...isn't the first shipment of rabidly freedom hating socialist/fascist/communist/anarchist Western psychopathic human shields supposed to leave for Iraq today?
Go to http://www.softwar.net/agm86.html
The B61 Mod 11 is a nuclear bomb intended to penetrate a significant distance into the ground before detonation.
Your understanding is incomplete. Non-nuclear bunker busters are of two types - deep penetration blast types, and daisy cutter types - suck all the oxygen out and atmospheric overpressure shock wave types.
Tactical nukes are a fine substitute - and are more effective in both the "dig 'em out" and "suck 'em out - blow 'em out" modes. In addition the nukes have some beneficial electrical effects that disable nearby electronic equipment that helps destroy the enemy's ability to communicate.
I am not a weapons expert - but read a bunch on the topic. Any corrections - additions are encouraged.