When does תלמידי חכמים אינם צריכים שמירה not apply?
I saw an interesting piece in one of the the weekly sheets that are distributed. They had the following question. There was a wave of burglaries in a particular Charedi neighborhood so the residents decided to hire a private security company. However, then the question of how to apportion the costs came up. Since the Gemara says that תלמידי חכמים אינם צריכים שמירה and the majority of the people in the neighborhood sit and learn in kollel (and presumably have the status of Talmidei Chachamim) who should pay? R' Elyashiv answered that the principle of תלמידי חכמים אינם צריכים שמירה only applies in a normal situation, before there is a rash of burglaries. However, now that there already was a rash of burglaries it would be considered a נס for the talmid chacham not to be harmed. Therefore the principle of תלמידי חכמים אינם צריכים שמירה does not apply and everyone has to pay equally for the security company.
When the issue of drafting yeshiva students for the army came up, this principle of תלמידי חכמים אינם צריכים שמירה was used as one of the reasons for the exemption. It would seem from the above that R' Elyashiv would disagree as it is as at least as much a נס to not be harmed in war/terrorist acts in Israel as not being burglarized where there is a rash of burglaries. In fact, at the time R' Zevin vehemently disagreed and made exactly this argument.