Russia-Ukraine war: Key things to know about the conflict


              An Ukrainian soldier exits a Psychiatric hospital damaged by a Russian bombing earlier this week, in Mykolaiv, Ukraine, Friday, 25, 2022. (AP Photo/Petros Giannakouris)
            
              A man repairs a damaged house by a Russian bombing earlier this week, in Mykolaiv, Ukraine, Friday, 25, 2022.(AP Photo/Petros Giannakouris)
            
              President Joe Biden arrives at Warsaw Chopin Airport, Friday, March 25, 2022, in Warsaw. Secretary of State Antony Blinken is second from right. (AP Photo/Evan Vucci)
            
              Lilu barks amid the destruction caused after a Russian attack in Podolskyi neighborhood, Kyiv, Ukraine, Friday, March 25, 2022. (AP Photo/ (AP Photo/Rodrigo Abd)
            
              Farmer Valerie Puzakovi, 56, left, poses for a picture with his wife Svitalna, a few block from their home in Yasnohorodka, a rural town where the Ukrainian army stopped the advance of the Russian army, outskirts of Kyiv, Ukraine, Friday, March 25, 2022. (AP Photo/ (AP Photo/Rodrigo Abd)
            
              A man enters a car to leave the area of a fire, following a Russian attack in Kharkiv, Ukraine, Friday, March 25, 2022. (AP Photo/Felipe Dana)
            
              A woman sweeps in front of her house, fragments of a Russian rocket in the foreground, following a Russian attack in Kharkiv, Ukraine, Friday, March 25, 2022. (AP Photo/Efrem Lukatsky)
            
              A Ukrainian flag is seen on top of a checkpoint as black smoke rises from a fuel storage of the Ukrainian army following a Russian attack, on the outskirts of Kyiv, Ukraine, Friday, March 25, 2022. (AP Photo/Rodrigo Abd)
            
              Firefighters battle a fire following a Russian attack in Kharkiv, Ukraine, Friday, March 25, 2022. (AP Photo/Felipe Dana)
            
              A family stays inside a subway station, being used as a bomb shelter, as Russian attacks continue in Kharkiv, Ukraine, Friday, March 25, 2022. (AP Photo/Felipe Dana)
            
              NATO Secretary General Jens Stoltenberg, second from right, greets soldiers during a visit to Bardufoss Military Airport, Norway March 25, 2022, in conjunction with the NATO Military Exercise Cold Response 22. (Annika Byrd /NTB scanpix via AP)
Russia-Ukraine war: Key things to know about the conflict