I also think minefields belong into OSM. Not sure however what’s the best way to tag it. As far as I understand most of the time approximate areas are known where there’s elevated risk of mines. While “military=danger_area” sounds like a good idea for areas which are really known as contaminated and often also have warning signs in place in the real world, it’s more difficult for areas where there may or not be mines. In the latter case, the military tag may not be appropriate. Example Bosnia: I recently added a lot of roads, tracks and paths, mostly based on sat images. However I’m now not so sure if that was a good idea, because some of those may be in dangerous areas, maybe without any signs in place (because distant from populated areas). The highest res mine map I could find online is http://www.jmu.edu/cisr/journal/9.1/Focus/marsic/hocevar_adriatic2_cmyk300.gif. That’s not enough for understanding where exactly those minefields are. I’ll try to find out more…