By Imtiaz Tyab, Agnes Reau, Tucker RealsNorthern Ukraine — The Ukrainian military has been conducting drills near the country's northern border with Belarus, aimed at showing preparedness to defend against any repeat of Russia's land invasion across that border. "Several Ukrainian units are now spread across the 650-mile frontier with Belarus, but they have yet to detect any new mass mobilization of Russian forces in the neighboring country.  We asked the soldier flying the drone, who goes by the callsign Kraken, what he was spending six hours every day scanning for