not necessarily, it depends on how the walls really were constructed. (although i doubt it is that well done) But rebar and cement can be wonderfully resilient, if the rebar is done in a dense enough mesh (really woven together nicely) even something like a bunker buster wouldn't be able to crack it. However that is quite expensive and time consuming to do.
Why crack the walls... I mean, if we're talking bunker buster level offensives I'm sure a couple of mortars, you know, going OVER the wall would solve the issue.
