Supplementary information
http://www.gnu.org/licenses/gpl-faq.html#NoMilitary
Q: I'd like to license my code under the GPL, but I'd also like to make it clear that it can't be used for military and/or commercial uses. Can I do this?

A: No, because those two goals contradict each other. The GNU GPL is designed specifically to prevent the addition of further restrictions. GPLv3 allows a very limited set of them, in section 7, but any other added restriction can be removed by the user.