Smoke rises after military strikes, as Russia's attack on Ukraine continues, in Lviv, Ukraine April 18, 2022. REUTERS/Roman Baluk 

Smoke rises after missile strikes, as Russia's attack on Ukraine continues, in Lviv, Ukraine April 18, 2022. REUTERS/Vladyslav Sodel 

A man walks near a residential building destroyed during Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

Service members of pro-Russian troops gather in a street during Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

A man rides a bicycle near a destroyed tank during Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

Armoured vehicles of pro-Russian troops drive along a road during Ukraine-Russia conflict near the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

A view shows a street, which was damaged during Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

A service member of pro-Russian troops sits on a chair in a street near a building, which was destroyed during Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

Service members of pro-Russian troops drive tanks during Ukraine-Russia conflict near the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

People walk along a street, which was damaged during Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

Service members of pro-Russian troops drive an armoured vehicle during Ukraine-Russia conflict near the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

People walk past the turret of a tank, which was destroyed during Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

Local residents sit in front of a block of flats burnt out during Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

Service members of pro-Russian troops help civilians to get on an armoured vehicle during Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

A passenger of a car speaks near the turret of a tank, which was destroyed during Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

People walk past the turret of a tank, which was destroyed during Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

A man walks past a residential building, which was destroyed during Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

Service members of pro-Russian troops sit atop of an armoured vehicle during Ukraine-Russia conflict near the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

A view shows a residential building, which was destroyed during Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

A view shows a residential building, which was destroyed during Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

A man walks along a street near a residential building, which was destroyed during Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

Local residents sit on a bench outside a residential building damaged during Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

A woman walks inside a building, which was damaged during Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

A view shows residential buildings destroyed during Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

Firefighters operate at a damaged apartment block following Russian shelling, amid Russia's attack on Ukraine, in Kharkiv, Ukraine, April 17, 2022. REUTERS/Alkis Konstantinidis 

A woman walks outside a residential building destroyed during Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 17, 2022. REUTERS/Alexander Ermochenko 

Firefighters operate at a damaged apartment block following Russian shelling, amid Russia's attack on Ukraine, in Kharkiv, Ukraine, April 17, 2022. REUTERS/Alkis Konstantinidis 

A man stands at the balcony of a damaged apartment following Russian shelling, amid Russia's attack on Ukraine, in Kharkiv, Ukraine, April 17, 2022. REUTERS/Alkis Konstantinidis 

A firefighter operates at a damaged apartment block following Russian shelling, amid Russia's attack on Ukraine, in Kharkiv, Ukraine, April 17, 2022. REUTERS/Alkis Konstantinidis 

Firefighters work at the site of military strikes on buildings as Russia's attack on Ukraine continues, in Lviv, Ukraine April 18, 2022. REUTERS/Pavlo Palamarchuk 

The coffin of Roman Vered, 53, who according to his family was killed by Russian soldiers and recently identified in Kyiv's morgue, is seen before his burial, as a gravedigger drinks water amid Russia's invasion of Ukraine, at the cemetery in Irpin, Kyiv region, Ukraine April 18, 2022. REUTERS/Zohra Bensemra 

Tetiana Vered, 53, mourns the death of her husband, Roman Vered, 53, who according to his family was killed by Russian soldiers and recently identified in Kyiv's morgue, as she stands with Anna Proidenko, 57, during his funeral, amid Russia's invasion of Ukraine, at the cemetery in Irpin, Kyiv region, Ukraine April 18, 2022. REUTERS/Zohra Bensemra 

Men inspect the site of military strikes on buildings as Russia's attack on Ukraine continues, in Lviv, Ukraine April 18, 2022. REUTERS/Pavlo Palamarchuk 

Firefighters work at the site of military strikes on buildings as Russia's attack on Ukraine continues, in Lviv, Ukraine April 18, 2022. REUTERS/Pavlo Palamarchuk 

Ukrainian servicemen and rescuers inspect the site of military strikes on buildings as Russia's attack on Ukraine continues, in Lviv, Ukraine April 18, 2022. REUTERS/Roman Baluk