A serviceman of the 18th brigade, army aviation, leaves an airfield after servicing a helicopter, after a mission on the frontline, amid Russia's invasion of Ukraine, at an airfield in Donetsk, Ukraine March 25, 2023. REUTERS/Violeta Santos Moura 

A Ukrainian helicopter of the 18th brigade, army aviation, takes off to carry out a mission on the frontline, amid Russia's invasion of Ukraine, at an airfield in Donetsk, Ukraine March 25, 2023. REUTERS/Violeta Santos Moura 

A pilot of the 18th brigade, army aviation, checks a helicopter after a mission on the frontline, amid Russia's invasion of Ukraine, at an airfield in Donetsk, Ukraine March 25, 2023. REUTERS/Violeta Santos Moura 

Servicemen of the 18th brigade, army aviation, refuel and service a helicopter after a mission on the frontline, amid Russia's invasion of Ukraine, at an airfield in Donetsk, Ukraine March 25, 2023. REUTERS/Violeta Santos Moura 

A serviceman of the 18th brigade, army aviation, resupplies a helicopter with ammunition after a mission on the frontline, amid Russia's invasion of Ukraine, at an airfield in Donetsk, Ukraine March 25, 2023. REUTERS/Violeta Santos Moura 

A Ukrainian pilot of the 18th brigade, army aviation, unholsters his pistol after a mission on the frontline, amid Russia's invasion of Ukraine, at an airfield in Donetsk, Ukraine March 25, 2023. REUTERS/Violeta Santos Moura 

Servicemen of the 18th brigade, army aviation, resupply a helicopter with ammunition, after a mission on the frontline, amid Russia's invasion of Ukraine, at an airfield in Donetsk, Ukraine March 25, 2023. REUTERS/Violeta Santos Moura 

A Ukrainian helicopter of the 18th brigade, army aviation, takes off to carry out a mission on the frontline, amid Russia's invasion of Ukraine, at an airfield in Donetsk, Ukraine March 25, 2023. REUTERS/Violeta Santos Moura 

A Ukrainian serviceman of the 18th brigade, army aviation, puts a weapon over his shoulder after a mission on the frontline, amid Russia's invasion of Ukraine, at an airfield in Donetsk, Ukraine March 25, 2023. REUTERS/Violeta Santos Moura 

A serviceman of the 18th brigade, army aviation, services a helicopter after a mission on the frontline, amid Russia's invasion of Ukraine, at an airfield in Donetsk, Ukraine March 25, 2023. REUTERS/Violeta Santos Moura 

A serviceman of the 18th brigade, army aviation, services a helicopter after a mission on the frontline, amid Russia's invasion of Ukraine, at an airfield in Donetsk, Ukraine March 25, 2023. REUTERS/Violeta Santos Moura 

A serviceman of the 18th brigade, army aviation, carries a missile from a helicopter after a mission on the frontline, amid Russia's invasion of Ukraine, at an airfield in Donetsk, Ukraine March 25, 2023. REUTERS/Violeta Santos Moura 

A Ukrainian artillery unit serviceman of the 45th Brigade fires a TRF1 howitzer towards Russian troops near the frontline town of Kreminna, amid Russia's attack on Ukraine, in Luhansk region, Ukraine March 24, 2023. REUTERS/Violeta Santos Moura 

A Ukrainian artillery unit serviceman of the 45th Brigade fires a TRF1 howitzer towards Russian troops near the frontline town of Kreminna, amid Russia's attack on Ukraine, in Luhansk region, Ukraine March 24, 2023. REUTERS/Violeta Santos Moura 

A Ukrainian artillery unit serviceman of the 45th Brigade fires a TRF1 howitzer towards Russian troops near the frontline town of Kreminna, amid Russia's attack on Ukraine, in Luhansk region, Ukraine March 24, 2023. REUTERS/Violeta Santos Moura 

Ukrainian artillery unit servicemen of the 45th Brigade await for orders to fire towards Russian troops near the frontline town of Kreminna, amid Russia's attack on Ukraine, in Luhansk region, Ukraine March 24, 2023. REUTERS/Violeta Santos Moura 

Ukrainian artillery unit servicemen of the 45th Brigade await in a dugout for orders to fire towards Russian troops near the frontline town of Kreminna, amid Russia's attack on Ukraine, in Luhansk region, Ukraine March 24, 2023. REUTERS/Violeta Santos Moura 

A Ukrainian artillery unit serviceman of the 45th Brigade awaits for orders to fire towards Russian troops near the frontline town of Kreminna, amid Russia's attack on Ukraine, in Luhansk region, Ukraine March 24, 2023. REUTERS/Violeta Santos Moura 

Ukrainian artillery unit servicemen of the 45th Brigade await for orders to fire towards Russian troops near the frontline town of Kreminna, amid Russia's attack on Ukraine, in Luhansk region, Ukraine March 24, 2023. REUTERS/Violeta Santos Moura 

Ukrainian artillery unit servicemen of the 45th Brigade await for orders to fire towards Russian troops near the frontline town of Kreminna, amid Russia's attack on Ukraine, in Luhansk region, Ukraine March 24, 2023. REUTERS/Violeta Santos Moura 

Ukrainian servicemen stand next to a destroyed building near the frontline town of Kreminna, amid Russia's attack on Ukraine, in Luhansk region, Ukraine March 24, 2023. REUTERS/Violeta Santos Moura TPX IMAGES OF THE DAY 

A Ukrainian artillery unit serviceman of the 45th Brigade smokes a cigarette while waiting for orders to fire towards Russian troops near the frontline town of Kreminna, amid Russia's attack on Ukraine, in Luhansk region, Ukraine March 24, 2023. REUTERS/Violeta Santos Moura 

A destroyed Ukrainian tank remains on the side of the road near the frontline town of Kreminna, amid Russia's attack on Ukraine, in Luhansk region, Ukraine March 24, 2023. REUTERS/Violeta Santos Moura 

A destroyed Russian tank remains on the side of the road near the frontline town of Kreminna, amid Russia's attack on Ukraine, in Luhansk region, Ukraine March 24, 2023. REUTERS/Violeta Santos Moura 

A destroyed Russian tank remains on the side of the road near the frontline town of Kreminna, amid Russia's attack on Ukraine, in Luhansk region, Ukraine March 24, 2023. REUTERS/Violeta Santos Moura 

A container with wheat is seen aboard Marshall Islands flagged general cargo ship Negmar Cicek loaded with wheat for Yemen, amid Russia's attack on Ukraine, in a sea port of the Chornomorsk town, Odesa region, Ukraine March 24, 2023. REUTERS/Stringer TPX IMAGES OF THE DAY 

U.S. ambassador to Ukraine Bridget Brink arrives aboard Marshall Islands flagged general cargo ship Negmar Cicek loaded with wheat for Yemen, amid Russia's attack on Ukraine, in a sea port of the Chornomorsk town, Odesa region, Ukraine March 24, 2023. REUTERS/Stringer 

Ukrainian servicemen prepare an unmanned aerial vehicle at a position near a frontline, amid Russia's attack on Ukraine, in Zaporizhzhia region, Ukraine March 23, 2023. REUTERS/Stringer 

Ukrainian servicemen prepare an unmanned aerial vehicle at a position near a frontline, amid Russia's attack on Ukraine, in Zaporizhzhia region, Ukraine March 23, 2023. REUTERS/Stringer 

A Ukrainian serviceman launches an unmanned aerial vehicle at a position near a frontline, amid Russia's attack on Ukraine, in Zaporizhzhia region, Ukraine March 23, 2023. REUTERS/Stringer 

Ukrainian servicemen prepare an unmanned aerial vehicle at a position near a frontline, amid Russia's attack on Ukraine, in Zaporizhzhia region, Ukraine March 23, 2023. REUTERS/Stringer TPX IMAGES OF THE DAY 

A Ukrainian serviceman rests at a position near a frontline, amid Russia's attack on Ukraine, in Zaporizhzhia region, Ukraine March 23, 2023. REUTERS/Stringer 

A Ukrainian serviceman holds an unmanned aerial vehicle at a position near a frontline, amid Russia's attack on Ukraine, in Zaporizhzhia region, Ukraine March 23, 2023. REUTERS/Stringer TPX IMAGES OF THE DAY 

Anti-aircraft unit serviceman of the 10th Mountain Assault Brigade, call sign "Kamin", 42, stands next to a number of portable anti-aircraft missile systems amid Russia's attack on Ukraine, near Soledar north of Bakhmut, Ukraine March 23, 2023. REUTERS/Violeta Santos Moura 

Anti-aircraft unit serviceman of the 10th Mountain Assault Brigade, call sign "Kamin", 42, emerges from a storage basement carrying a portable anti-aircraft missile system, amid Russia's attack on Ukraine, near Soledar north of Bakhmut, Ukraine March 23, 2023. REUTERS/Violeta Santos Moura 

Anti-aircraft unit serviceman of the 10th Mountain Assault Brigade, call sign "Kamin", 42, explains how to fire a Stinger portable anti-aircraft missile amid Russia's attack on Ukraine, near Soledar north of Bakhmut, Ukraine March 23, 2023. REUTERS/Violeta Santos Moura 

Anti-aircraft unit serviceman of the 10th Mountain Assault Brigade, call sign "Chub", 34, emerges from a storage basement with a portable anti-aircraft missile system amid Russia's attack on Ukraine, near Soledar north of Bakhmut, Ukraine March 23, 2023. REUTERS/Violeta Santos Moura 

Anti-aircraft unit serviceman of the 10th Mountain Assault Brigade, call sign "Kamin", 42, emerges from a storage basement carrying portable anti-aircraft missile systems, amid Russia's attack on Ukraine, near Soledar north of Bakhmut, Ukraine March 23, 2023. REUTERS/Violeta Santos Moura 

Anti-aircraft unit serviceman of the 10th Mountain Assault Brigade, call sign "Chub", 34, poses for a portrait with a portable anti-aircraft missile system, amid Russia's attack on Ukraine, near Soledar north of Bakhmut, Ukraine March 23, 2023. REUTERS/Violeta Santos Moura 

Anti-aircraft unit serviceman of the 10th Mountain Assault Brigade, call sign "Chub", 34, prepares to pose for a portrait with a portable anti-aircraft missile system, amid Russia's attack on Ukraine, near Soledar north of Bakhmut, Ukraine March 23, 2023. REUTERS/Violeta Santos Moura 

Portable anti-aircraft missile systems lean against a wall, amid Russia's attack on Ukraine, near Soledar north of Bakhmut, Ukraine March 23, 2023. REUTERS/Violeta Santos Moura 

Shelest Oleksandr and his wife Vira, who were wounded during Russian drone attacks on a compound of a local lyceum in the town of Rzhyshchiv, are seen in a hospital of the Obukhiv town, amid Russia's attack on Ukraine, in Kyiv region, Ukraine March 22, 2023. REUTERS/Ivan Lyubysh-Kirdey 

Shelest Oleksandr and his wife Vira, who were wounded during Russian drone attacks on a compound of a local lyceum in the town of Rzhyshchiv, are seen in a hospital of the Obukhiv town, amid Russia's attack on Ukraine, in Kyiv region, Ukraine March 22, 2023. REUTERS/Ivan Lyubysh-Kirdey 

A doctor stands next to Shelest Oleksandr and his wife Vira, who were wounded during Russian drone attacks on a compound of a local lyceum in the town of Rzhyshchiv, in a hospital of the Obukhiv town, amid Russia's attack on Ukraine, in Kyiv region, Ukraine March 22, 2023. REUTERS/Ivan Lyubysh-Kirdey 

A security personnel stands guard at a site of a building heavily damaged by Russian drone strikes, amid Russia's attack on Ukraine, in the town of Rzhyshchiv, in Kyiv region, Ukraine March 22, 2023. REUTERS/Alina Yarysh 

A rescuer works at a site of a building heavily damaged by Russian drone strikes, amid Russia's attack on Ukraine, in the town of Rzhyshchiv, in Kyiv region, Ukraine March 22, 2023. REUTERS/Alina Yarysh 

Rescuers work at a site of a building heavily damaged by Russian drone strikes, amid Russia's attack on Ukraine, in the town of Rzhyshchiv, in Kyiv region, Ukraine March 22, 2023. REUTERS/Alina Yarysh 

A security personnel stands guard at a site of a building heavily damaged by Russian drone strikes, amid Russia's attack on Ukraine, in the town of Rzhyshchiv, in Kyiv region, Ukraine March 22, 2023. REUTERS/Alina Yarysh 

A police officer stands guard as rescuers work at a site of a building heavily damaged by Russian drone strikes, amid Russia's attack on Ukraine, in the town of Rzhyshchiv, in Kyiv region, Ukraine March 22, 2023. REUTERS/Alina Yarysh 

Police officers stand guard as rescuers work at a site of a building heavily damaged by Russian drone strikes, amid Russia's attack on Ukraine, in the town of Rzhyshchiv, in Kyiv region, Ukraine March 22, 2023. REUTERS/Alina Yarysh 

A view shows a residential building damaged by a Russian missile strike, amid Russia's attack on Ukraine, in Zaporizhzhia, Ukraine March 22, 2023. REUTERS/Stringer 

Rescuers work at a site of a residential building damaged by a Russian missile strike, amid Russia's attack on Ukraine, in Zaporizhzhia, Ukraine March 22, 2023. REUTERS/Stringer 

Rescuers work at a site of a residential building damaged by a Russian missile strike, amid Russia's attack on Ukraine, in Zaporizhzhia, Ukraine March 22, 2023. REUTERS/Stringer TPX IMAGES OF THE DAY 

A rescuer stands in front of a residential building damaged by a Russian missile strike, amid Russia's attack on Ukraine, in Zaporizhzhia, Ukraine March 22, 2023. REUTERS/Stringer 

A view shows a residential building damaged by a Russian missile strike, amid Russia's attack on Ukraine, in Zaporizhzhia, Ukraine March 22, 2023. REUTERS/Stringer 

A view shows a residential building damaged by a Russian missile strike, amid Russia's attack on Ukraine, in Zaporizhzhia, Ukraine March 22, 2023. REUTERS/Stringer 

A view shows a residential building damaged by a Russian missile strike, amid Russia's attack on Ukraine, in Zaporizhzhia, Ukraine March 22, 2023. REUTERS/Stringer 

Medics carry a man evacuated from a residential building damaged by a Russian missile strike, amid Russia's attack on Ukraine, in Zaporizhzhia, Ukraine March 22, 2023. REUTERS/Stringer 

A view of a residential building damaged by a Russian missile strike, amid Russia's attack on Ukraine, in Zaporizhzhia, Ukraine March 22, 2023. REUTERS/Stringer 

A damaged car is seen next to a residential building hit by a Russian missile strike, amid Russia's attack on Ukraine, in Zaporizhzhia, Ukraine March 22, 2023. REUTERS/Stringer