WASHINGTON—Widely available commercial satellite imagery of Russian troop positions bracketing Ukraine provides a bird’s-eye view of an international crisis as it unfolds. But the pictures, while dramatic, have limitations. High-resolution photos from commercial satellite companies like Maxar in recent days showed Russian troop assembly areas, airfields, artillery positions and other activities on the Russian side of the Ukrainian border and in southern Belarus as well as on the Crimean Peninsula, which Russia seized from Ukraine in 2014. The images confirmed what U.S. and other Western officials have been saying: Russian forces are arrayed within striking distances of Ukraine. But they could not provide conclusive information about net additions or subtractions of Russian forces or reveal when or whether an invasion of Ukraine would happen. In such a fluid crisis, even day-old satellite photos might miss significant changes on the ground. Western officials, citing their own sources of information, have disputed …