According to an aspect of the invention, there is provided a fuze arming system for a submunition, comprising: a first stage, arranged to detect launch of the submunition and its associated carrier; a second stage, arranged to detect expulsion of the submunition from the carrier, and to at least partially arm a submunition fuze based on such detection; wherein the second stage is unable to at least partially arm the submunition fuze without the first stage detecting launch of the submunition and its associated carrier.