Biggest News aggregator with 200 million news articles | com
>> so, they're using to correct the shell is fired. >> reporter: a note they must keep hidden. [ speaking in a non-english language ] >> reporter: there's still the basic problem that it's trench warfare and mine fields. and that, by definition, makes the going slow. but as the sky darken and the air cools here, an advantage has emerged. one of their drones is equipped with a thermal camera, and they've noticed out in the wide cratered fields, about four kilometers away where the russians hide, something new. some of these white dots are russian land mines. they're attained through the heat of the summer sun, as the earth around them cools. the contrast is greatest at dusk or dawn, experts say.