I can only answer the first question about visibility since I read a response previously on it. Basically, the overgrowth moves quick so you can’t see anything with plant coverage pretty quickly. Also rain and snow cover tracks and flatten out the soil that would have been disturbed. Comes down to, can’t see any of them unless you are up close and personal…and even then you need to be trained to spot them. As for blowing them up, they’ve been placed everywhere by the Russians. You can’t explode a few thousand square kilometers (I mean short of doing something crazy).