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


              A man walks in his apartment ruined after the Russian shelling in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Efrem Lukatsky)
            
              Worker Ruslan Trishchuk, 40, smokes a cigarette while taking a break outside the crematorium of Baikave cemetery in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Rodrigo Abd)
            
              Daryna Kovalenko, 19 , holds her dog Tim, while arriving at Kyiv's train station after leaving her home in Chernihiv, Ukraine, through a humanitarian corridor, Monday, March 21, 2022. (AP Photo/ (AP Photo/Rodrigo Abd)
            
              In this image from video provided by the Ukrainian Presidential Press Office, Ukrainian President Volodymyr Zelenskyy speaks from Kyiv, Ukraine, on Monday, March 21, 2022. (Ukrainian Presidential Press Office via AP)
            
              Civilian volunteers carry unloaded rifles during a training camp of the Ukrainian Territorial Defense Forces in Brovary, northeast of Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Felipe Dana)
            
              Volunteers cook in the courtyard of a theatre in the city of Drohobych, western Ukraine, Monday, March 21, 2022. The theatre has become a meeting point, where artists, including those displaced from other parts of Ukraine, have turned their talents to making food for soldiers and others as part of a massive volunteer war effort across the country. (AP Photo/Bernat Armangue)
            
              People gather amid the destruction caused after shelling of a shopping center, in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/ (AP Photo/Rodrigo Abd)
            
              Slava Chikov covers the shattered window of his living room with a plastic sheet in a building damaged by a bombing the previous day in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Vadim Ghirda)
            
              A woman measures a window before covering it with plastic sheets in a building damaged by a bombing the previous day in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Vadim Ghirda)
            
              Serhii Volosovets, a commander in the Ukrainian Territorial Defense Forces, fires a pistol during a training camp for volunteers in Brovary, northeast of Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Felipe Dana)
            
              Ukrainian firefighters and servicemen search for people under debris inside a shopping center after bombing in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Felipe Dana)
            
              A man walks in his apartment ruined after the Russian shelling in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Efrem Lukatsky)
            
              Worker Ruslan Trishchuk, 40, smokes a cigarette while taking a break outside the crematorium of Baikave cemetery in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Rodrigo Abd)
            
              Daryna Kovalenko, 19 , holds her dog Tim, while arriving at Kyiv's train station after leaving her home in Chernihiv, Ukraine, through a humanitarian corridor, Monday, March 21, 2022. (AP Photo/ (AP Photo/Rodrigo Abd)
            
              In this image from video provided by the Ukrainian Presidential Press Office, Ukrainian President Volodymyr Zelenskyy speaks from Kyiv, Ukraine, on Monday, March 21, 2022. (Ukrainian Presidential Press Office via AP)
            
              Civilian volunteers carry unloaded rifles during a training camp of the Ukrainian Territorial Defense Forces in Brovary, northeast of Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Felipe Dana)
            
              Volunteers cook in the courtyard of a theatre in the city of Drohobych, western Ukraine, Monday, March 21, 2022. The theatre has become a meeting point, where artists, including those displaced from other parts of Ukraine, have turned their talents to making food for soldiers and others as part of a massive volunteer war effort across the country. (AP Photo/Bernat Armangue)
            
              People gather amid the destruction caused after shelling of a shopping center, in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/ (AP Photo/Rodrigo Abd)
            
              Slava Chikov covers the shattered window of his living room with a plastic sheet in a building damaged by a bombing the previous day in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Vadim Ghirda)
            
              A woman measures a window before covering it with plastic sheets in a building damaged by a bombing the previous day in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Vadim Ghirda)
            
              Serhii Volosovets, a commander in the Ukrainian Territorial Defense Forces, fires a pistol during a training camp for volunteers in Brovary, northeast of Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Felipe Dana)
            
              Ukrainian firefighters and servicemen search for people under debris inside a shopping center after bombing in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Felipe Dana)
            
              A man walks in his apartment ruined after the Russian shelling in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Efrem Lukatsky)
            
              Worker Ruslan Trishchuk, 40, smokes a cigarette while taking a break outside the crematorium of Baikave cemetery in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Rodrigo Abd)
            
              Daryna Kovalenko, 19 , holds her dog Tim, while arriving at Kyiv's train station after leaving her home in Chernihiv, Ukraine, through a humanitarian corridor, Monday, March 21, 2022. (AP Photo/ (AP Photo/Rodrigo Abd)
            
              In this image from video provided by the Ukrainian Presidential Press Office, Ukrainian President Volodymyr Zelenskyy speaks from Kyiv, Ukraine, on Monday, March 21, 2022. (Ukrainian Presidential Press Office via AP)
            
              Civilian volunteers carry unloaded rifles during a training camp of the Ukrainian Territorial Defense Forces in Brovary, northeast of Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Felipe Dana)
            
              Volunteers cook in the courtyard of a theatre in the city of Drohobych, western Ukraine, Monday, March 21, 2022. The theatre has become a meeting point, where artists, including those displaced from other parts of Ukraine, have turned their talents to making food for soldiers and others as part of a massive volunteer war effort across the country. (AP Photo/Bernat Armangue)
            
              People gather amid the destruction caused after shelling of a shopping center, in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/ (AP Photo/Rodrigo Abd)
            
              Slava Chikov covers the shattered window of his living room with a plastic sheet in a building damaged by a bombing the previous day in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Vadim Ghirda)
            
              A woman measures a window before covering it with plastic sheets in a building damaged by a bombing the previous day in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Vadim Ghirda)
            
              Serhii Volosovets, a commander in the Ukrainian Territorial Defense Forces, fires a pistol during a training camp for volunteers in Brovary, northeast of Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Felipe Dana)
            
              Ukrainian firefighters and servicemen search for people under debris inside a shopping center after bombing in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Felipe Dana)
            
              A man walks in his apartment ruined after the Russian shelling in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Efrem Lukatsky)
            
              Worker Ruslan Trishchuk, 40, smokes a cigarette while taking a break outside the crematorium of Baikave cemetery in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Rodrigo Abd)
            
              Daryna Kovalenko, 19 , holds her dog Tim, while arriving at Kyiv's train station after leaving her home in Chernihiv, Ukraine, through a humanitarian corridor, Monday, March 21, 2022. (AP Photo/ (AP Photo/Rodrigo Abd)
            
              In this image from video provided by the Ukrainian Presidential Press Office, Ukrainian President Volodymyr Zelenskyy speaks from Kyiv, Ukraine, on Monday, March 21, 2022. (Ukrainian Presidential Press Office via AP)
            
              Civilian volunteers carry unloaded rifles during a training camp of the Ukrainian Territorial Defense Forces in Brovary, northeast of Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Felipe Dana)
            
              Volunteers cook in the courtyard of a theatre in the city of Drohobych, western Ukraine, Monday, March 21, 2022. The theatre has become a meeting point, where artists, including those displaced from other parts of Ukraine, have turned their talents to making food for soldiers and others as part of a massive volunteer war effort across the country. (AP Photo/Bernat Armangue)
            
              People gather amid the destruction caused after shelling of a shopping center, in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/ (AP Photo/Rodrigo Abd)
            
              Slava Chikov covers the shattered window of his living room with a plastic sheet in a building damaged by a bombing the previous day in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Vadim Ghirda)
            
              A woman measures a window before covering it with plastic sheets in a building damaged by a bombing the previous day in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Vadim Ghirda)
            
              Serhii Volosovets, a commander in the Ukrainian Territorial Defense Forces, fires a pistol during a training camp for volunteers in Brovary, northeast of Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Felipe Dana)
            
              Ukrainian firefighters and servicemen search for people under debris inside a shopping center after bombing in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Felipe Dana)
            
              A man walks in his apartment ruined after the Russian shelling in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Efrem Lukatsky)
            
              Worker Ruslan Trishchuk, 40, smokes a cigarette while taking a break outside the crematorium of Baikave cemetery in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Rodrigo Abd)
            
              Daryna Kovalenko, 19 , holds her dog Tim, while arriving at Kyiv's train station after leaving her home in Chernihiv, Ukraine, through a humanitarian corridor, Monday, March 21, 2022. (AP Photo/ (AP Photo/Rodrigo Abd)
            
              In this image from video provided by the Ukrainian Presidential Press Office, Ukrainian President Volodymyr Zelenskyy speaks from Kyiv, Ukraine, on Monday, March 21, 2022. (Ukrainian Presidential Press Office via AP)
            
              Civilian volunteers carry unloaded rifles during a training camp of the Ukrainian Territorial Defense Forces in Brovary, northeast of Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Felipe Dana)
            
              Volunteers cook in the courtyard of a theatre in the city of Drohobych, western Ukraine, Monday, March 21, 2022. The theatre has become a meeting point, where artists, including those displaced from other parts of Ukraine, have turned their talents to making food for soldiers and others as part of a massive volunteer war effort across the country. (AP Photo/Bernat Armangue)
            
              People gather amid the destruction caused after shelling of a shopping center, in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/ (AP Photo/Rodrigo Abd)
            
              Slava Chikov covers the shattered window of his living room with a plastic sheet in a building damaged by a bombing the previous day in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Vadim Ghirda)
            
              A woman measures a window before covering it with plastic sheets in a building damaged by a bombing the previous day in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Vadim Ghirda)
            
              Serhii Volosovets, a commander in the Ukrainian Territorial Defense Forces, fires a pistol during a training camp for volunteers in Brovary, northeast of Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Felipe Dana)
            
              Ukrainian firefighters and servicemen search for people under debris inside a shopping center after bombing in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Felipe Dana)
            
              A man walks in his apartment ruined after the Russian shelling in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Efrem Lukatsky)
            
              Worker Ruslan Trishchuk, 40, smokes a cigarette while taking a break outside the crematorium of Baikave cemetery in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Rodrigo Abd)
            
              Daryna Kovalenko, 19 , holds her dog Tim, while arriving at Kyiv's train station after leaving her home in Chernihiv, Ukraine, through a humanitarian corridor, Monday, March 21, 2022. (AP Photo/ (AP Photo/Rodrigo Abd)
            
              In this image from video provided by the Ukrainian Presidential Press Office, Ukrainian President Volodymyr Zelenskyy speaks from Kyiv, Ukraine, on Monday, March 21, 2022. (Ukrainian Presidential Press Office via AP)
            
              Civilian volunteers carry unloaded rifles during a training camp of the Ukrainian Territorial Defense Forces in Brovary, northeast of Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Felipe Dana)
            
              Volunteers cook in the courtyard of a theatre in the city of Drohobych, western Ukraine, Monday, March 21, 2022. The theatre has become a meeting point, where artists, including those displaced from other parts of Ukraine, have turned their talents to making food for soldiers and others as part of a massive volunteer war effort across the country. (AP Photo/Bernat Armangue)
            
              People gather amid the destruction caused after shelling of a shopping center, in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/ (AP Photo/Rodrigo Abd)
            
              Slava Chikov covers the shattered window of his living room with a plastic sheet in a building damaged by a bombing the previous day in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Vadim Ghirda)
            
              A woman measures a window before covering it with plastic sheets in a building damaged by a bombing the previous day in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Vadim Ghirda)
            
              Serhii Volosovets, a commander in the Ukrainian Territorial Defense Forces, fires a pistol during a training camp for volunteers in Brovary, northeast of Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Felipe Dana)
            
              Ukrainian firefighters and servicemen search for people under debris inside a shopping center after bombing in Kyiv, Ukraine, Monday, March 21, 2022. (AP Photo/Felipe Dana)
            
              A Ukrainian serviceman walks on the outskirts of Kyiv, Ukraine, Sunday, March 20, 2022. Russian forces pushed deeper into Ukraine's besieged and battered port city of Mariupol on Saturday, where heavy fighting shut down a major steel plant and local authorities pleaded for more Western help. (AP Photo/Vadim Ghirda)
            
              A woman holds a child in an improvised bomb shelter in Mariupol, Ukraine, Monday, March 7, 2022. (AP Photo/Mstyslav Chernov)
            
              Medical workers treat a man, wounded by shelling, in a hospital in Mariupol, Ukraine, Friday, March 4, 2022. (AP Photo/Mstyslav Chernov)
            
              In this image from video provided by the Ukrainian Presidential Press Office, Ukrainian President Volodymyr Zelenskyy speaks from Kyiv, Ukraine, early Monday, March 21, 2022. (Ukrainian Presidential Press Office via AP)
            
              A Ukrainian bomb squad inspect the site of an explosion after bombing in Kyiv, Ukraine, Sunday, March 20, 2022. (AP Photo/Felipe Dana)
            
              A refugee woman eats in Brovary, Ukraine, Sunday, March 20, 2022, after 1,600 people, of which half are children according to authorities, were evacuated from the village of Bobrik, reportedly under Russian military control. Russian forces pushed deeper into Ukraine's besieged and battered port city of Mariupol on Saturday, where heavy fighting shut down a major steel plant and local authorities pleaded for more Western help. (AP Photo/Vadim Ghirda)
            
              Ukrainians escaping from the besieged city of Mariupol along with other passengers from Zaporizhzhia arrive at Lviv, western Ukraine, on Sunday, March 20, 2022. (AP Photo/Bernat Armangue)
            
              Bogdana, 17, kisses her boyfriend, Ivan, 19, in Brovary, Ukraine, Sunday, March 20, 2022. Russian forces pushed deeper into Ukraine's besieged and battered port city of Mariupol on Saturday, where heavy fighting shut down a major steel plant and local authorities pleaded for more Western help. (AP Photo/Vadim Ghirda)
            
              Debris covers a damaged kitchen at an apartment building hit by shelling in Kharkiv, Ukraine, Sunday, March 20, 2022. (AP Photo/Andrew Marienko)
            
              A refugee woman holds a baby while waiting on a bus for Ukrainian police to check papers and belongings in Brovary, Ukraine, Sunday, March 20, 2022, after 1,600 people, of which half children according to authorities, were evacuated from the village of Bobrik, reportedly under Russian military control. Russian forces pushed deeper into Ukraine's besieged and battered port city of Mariupol on Saturday, where heavy fighting shut down a major steel plant and local authorities pleaded for more Western help. (AP Photo/Vadim Ghirda)
            
              People gather outside their destroyed buildings after a bombing in Satoya neighborhood in Kyiv, Ukraine, Sunday, March 20, 2022. (AP Photo/Rodrigo Abd)
            
              Ukrainian servicemen rest inside a bunker on the outskirts of Kyiv, Ukraine, Sunday, March 20, 2022. Russian forces pushed deeper into Ukraine's besieged and battered port city of Mariupol on Saturday, where heavy fighting shut down a major steel plant and local authorities pleaded for more Western help. (AP Photo/Vadim Ghirda)