ITT: Splitting hairs, pointlessly.

A modern day ninja would happily use guns. Or bombs. Or atomic weapons, if necessary. (Of ocurse, the "bad ass spy" part of an atomic weapon mission would be smuggling the thing in, undetected. Otherwise, a modern country would just use a strategic bomber or ICBM.)

Ninja-ness is defined by the relationship to the fedual lord/country leader.