simple question to answer, but u.s. defense officials have been unable to identify a commander. that could explain the commanding control problems that russian troops have had so far. according to the pentagon, russia has failed to achieve most of its military objective in this country. cnn's katie bo lil lis live in washington with her reporting on this. what have you learned? >> reporter: yeah, john. multiple u.s. officials say multiple sources familiar with the matter, not all u.s. officials, have told us that the united states has been unable to determine exactly who the top senior leader, the top military leader on the ground leading russian troops in ukraine is. the kind of theater-wide commander that the united states would anticipate that russia or any professional military would put into place to run its war in a coherent fashion. now, the russian ministry of defense has declined to respond to request for comment from cnn, but our sources tell us that