Yes, any given shelter is vulnerable to bunker-busters, but if you have multiple hardened sites, not all will be hit, as the ones holding populations have little strategic value.
Its a numbers game, and we are stupid to be unprepared.
It would be immoral to use bunker busters on said civilian shetlers UNLESS they were holding military needs.
My scenario for the doom of the USA....a few dirty suitcase nukes...one each in NYC, Washington, DC, Chicago, Seattle, San Fran & LA.
While we are on our knees dealing with said attack, China can deliver the coup-de-grace. Game Over!
And don't think for a moment that can't happen.
Anyone that votes Democratic is either stupid or un-American.