By Idrees Ali and Phil Stewart WASHINGTON (Reuters) -Russia’s military move on Kyiv has stalled as its forces struggle with basic logistics challenges, including shortages of food and fuel, with some units appearing to be gripped by low morale, a senior U.S. defense official said on Tuesday. Russia warned residents in capital Kyiv to flee their homes on Tuesday and rained rockets down on the second city of Kharkiv, as Russian commanders who have failed to achieve a quick victory shifted their tactics to intensify the bombardment of Ukrainian cities. Satellite images taken on Monday show a Russ…