A service member of pro-Russian troops fires an anti-tank grenade launcher during fighting in Ukraine-Russia conflict in the besieged southern port city of Mariupol, Ukraine March 31, 2022. REUTERS/Alexander Ermochenko 

Service members of pro-Russian troops carry an anti-tank grenade launcher during fighting in Ukraine-Russia conflict in the besieged southern port city of Mariupol, Ukraine March 31, 2022. REUTERS/Alexander Ermochenko 

An armoured vehicle of pro-Russian troops drives along a street past a residential building destroyed during Ukraine-Russia conflict in the besieged southern port city of Mariupol, Ukraine March 31, 2022. REUTERS/Alexander Ermochenko 

Zamid Chalaev regiment commander from Chechen Republic fires an automatic grenade launcher during fighting in Ukraine-Russia conflict in the city of Mariupol, Ukraine March 31, 2022. REUTERS/Chingis Kondarov 

Service members of pro-Russian troops carry a body of a serviceman killed in fighting in Ukraine-Russia conflict in the city of Mariupol, Ukraine March 31, 2022. REUTERS/Chingis Kondarov 

A service member of pro-Russian troops carries projectiles for an anti-tank grenade launcher during fighting in Ukraine-Russia conflict in the besieged southern port city of Mariupol, Ukraine March 31, 2022. REUTERS/Alexander Ermochenko 

A service member from Chechen Republic aims his rifle during fighting in Ukraine-Russia conflict in the city of Mariupol, Ukraine March 31, 2022. REUTERS/Chingis Kondarov 

Parts of ammunition and shell casings lie next to a destroyed car in a residential area during Ukraine-Russia conflict in the besieged southern port city of Mariupol, Ukraine March 31, 2022. REUTERS/Alexander Ermochenko 

A local resident speaks to a service member of pro-Russian troops outside an apartment building damaged during Ukraine-Russia conflict in the besieged southern port city of Mariupol, Ukraine March 31, 2022. REUTERS/Alexander Ermochenko 

A local resident carries a sack near an apartment building destroyed during Ukraine-Russia conflict in the besieged southern port city of Mariupol, Ukraine March 31, 2022. REUTERS/Alexander Ermochenko 

A local resident walks past shell casings in front of an apartment building damaged during Ukraine-Russia conflict in the besieged southern port city of Mariupol, Ukraine March 31, 2022. REUTERS/Alexander Ermochenko 

Service members from Chechen Republic are seen on positions during fighting in Ukraine-Russia conflict in the city of Mariupol, Ukraine March 31, 2022. REUTERS/Chingis Kondarov 

Service members of pro-Russian troops look on as they ride an armoured vehicle during fighting in Ukraine-Russia conflict in the city of Mariupol, Ukraine March 31, 2022. REUTERS/Chingis Kondarov 

Service members from Chechen Republic walk during fighting in Ukraine-Russia conflict in the city of Mariupol, Ukraine March 31, 2022. REUTERS/Chingis Kondarov 

A local resident pushes a cart past a building damaged during Ukraine-Russia conflict in the besieged southern port city of Mariupol, Ukraine March 31, 2022. REUTERS/Alexander Ermochenko 

Graves are seen next to an apartment building during Ukraine-Russia conflict in the besieged southern port city of Mariupol, Ukraine March 31, 2022. REUTERS/Alexander Ermochenko 

Service members of pro-Russian troops are seen atop of an armoured vehicle in the course of Ukraine-Russia conflict in the besieged southern port city of Mariupol, Ukraine March 30, 2022. REUTERS/Alexander Ermochenko