I work in the defense industry. I have a personal philosophy that I will never work on a platform that could be used to directly or even indirectly harm an individual person (like a fighter jet radar system). So far I've been able to stick to it. While I do think offensive weapons are a necessary part of life in these times, I don't want any of my work going towards building them. Of course some of the profit I help my company make likely goes towards developing new offensive weapons, my taxes will always fund my government's purchase and use of these weapons no matter who I work for.