francis. he said very important words. i understand that you long for peace. i understand that you need to defend yourselves. >> reporter: among the growing number of issues that russian troops are now facing in ukraine is the cold. according to a senior u.s. defense official, on top of the food and fuel issues, the logistical and communications issues that russian troops are facing at the front, the u.s. is also seeing signs that some russian troops have also come down with frostbite and have had to be taken out of the fight in ukraine. alex marquardt, cnn, at the state department. well, the kremlin spokesperson, dmitry peskov, admits that russian president vladimir putin has not achieved his military goals in ukraine. peskov spoke exclusively with cnn's christiane amanpour, and he refused to deny that russia could resort to nuclear weapons. >> you can read all the reasons