British soldiers prepare for Swift Response 22 exercises carried out by NATO allied troops, during a media open day at Krivolak army base, North Macedonia, May 12, 2022. REUTERS/Ognen Teofilovski

Romanian helicopter Puma 330 is seen as Romanian, British and U.S. maritime NATO forces carry out 'Exercise Trojan Footprint' exercises during a media tour of the special operations at sea off Constanta, Romania, May 9, 2022. REUTERS/Remo Casilli

A British soldier prepares for Swift Response 22 exercises carried out by NATO allied troops, during a media open day at Krivolak army base, North Macedonia, May 12, 2022. REUTERS/Ognen Teofilovski

People watch self-propelled guns, Panzerhaubitze 2000, during training at a German army base on a NATO media day, in which up to 7,500 soldiers from 9 nations take part, in Munster, Germany, May 10, 2022. REUTERS/Fabian Bimmer

Soldiers walk on board the ship Vice Admiral Constantin Balescu 274 as Romanian, British and U.S. maritime NATO forces carry out 'Exercise Trojan Footprint' exercises during a media tour of the special operations at sea off Constanta, Romania, May 9, 2022. REUTERS/Remo Casilli

Soldiers shoot from a howitzer during training at a German army base on a NATO media day, in which up to 7,500 soldiers from 9 nations take part, in Munster, Germany, May 10, 2022. REUTERS/Fabian Bimmer

Ammunition for a howitzer is seen during training at a German army base on a NATO media day, in which up to 7,500 soldiers from 9 nations take part, in Munster, Germany, May 10, 2022. REUTERS/Fabian Bimmer

Soldiers participate in 'Flaming Sword' training carried out by NATO allied troops, during a media tour of the special operations, in Klaipeda, Lithuania, May 11, 2022. REUTERS/Remo Casilli

A British soldier prepares for Swift Response 22 exercises carried out by NATO allied troops, during a media open day at Krivolak army base, North Macedonia, May 12, 2022. REUTERS/Ognen Teofilovski

British soldiers prepare for Swift Response 22 exercises carried out by NATO allied troops, during a media open day at Krivolak army base, North Macedonia, May 12, 2022. REUTERS/Ognen Teofilovski

Belgian soldiers prepare ammunition for a howitzer during training at a German army base on a NATO media day, in which up to 7,500 soldiers from 9 nations take part, in Munster, Germany, May 10, 2022. REUTERS/Fabian Bimmer

British soldiers deploy for an exercise as NATO allied troops carry out Swift Response 22 exercises during a media open day at Krivolak army base, North Macedonia, May 12, 2022. REUTERS/Ognen Teofilovski

A Romanian soldier uses an M240 machine gun on board a vessel as Romanian, British and U.S. maritime NATO forces carry out 'Exercise Trojan Footprint' exercises during a media tour of the special operations at sea off Constanta, Romania, May 9, 2022. REUTERS/Remo Casilli

Belgian soldiers take part in training at a German army base on a NATO media day, in which up to 7,500 soldiers from 9 nations take part, in Munster, Germany, May 10, 2022. REUTERS/Fabian Bimmer

Self-propelled guns, Panzerhaubitze 2000, are seen during training at a German army base on a NATO media day, in which up to 7,500 soldiers from 9 nations take part, in Munster, Germany, May 10, 2022. REUTERS/Fabian Bimmer

Spanish troops of NATO enhanced Forward Presence battlegroup prepare for Iron Spear 2022 military exercise in Adazi military field, Latvia May 11, 2022. REUTERS/Ints Kalnins

Soldiers take position during training at a German army base on a NATO media day, in which up to 7,500 soldiers from 9 nations take part, in Munster, Germany, May 10, 2022. REUTERS/Fabian Bimmer

Italian paratroopers jump from a C-130 aircraft as NATO allied troops carry out Swift Response 22 exercises during a media open day at Krivolak army base, North Macedonia, May 12, 2022. REUTERS/Ognen Teofilovski

Britain's flag shutters during media day of NATO military exercise in Rukla, Lithuania May 10, 2022. REUTERS/Janis Laizans

U.S. Black Hawk helicopters fly as NATO allied troops carry out Swift Response 22 exercises during a media open day at Krivolak army base, North Macedonia, May 12, 2022. REUTERS/Ognen Teofilovski

German and Canadian troops of NATO enhanced Forward Presence battlegroup prepare during Iron Spear 2022 military exercise in Adazi military field, Latvia May 11, 2022. REUTERS/Ints Kalnins

A soldier takes position during training at a German army base on a NATO media day, in which up to 7,500 soldiers from 9 nations take part, in Munster, Germany, May 10, 2022. REUTERS/Fabian Bimmer

Soldiers run near an Mi-17 helicopter as they participate in 'Flaming Sword' training carried out by NATO allied troops, during a media tour of the special operations, in Klaipeda, Lithuania, May 11, 2022. REUTERS/Remo Casilli

Norwegian troops of NATO enhanced Forward Presence battlegroup prepare for Iron Spear 2022 military exercise in Adazi military field, Latvia May 11, 2022. REUTERS/Ints Kalnins

A soldier hangs on a rope attached to Romanian helicopter Puma 330 as Romanian, British and U.S. maritime NATO forces carry out 'Exercise Trojan Footprint' exercises during a media tour of the special operations at sea off Constanta, Romania, May 9, 2022. REUTERS/Remo Casilli

A soldier looks through binoculars during training at a German army base on a NATO media day, in which up to 7,500 soldiers from 9 nations take part, in Munster, Germany, May 10, 2022. REUTERS/Fabian Bimmer

Latvian and U.S. medical NATO forces move a mannequin, as part of 'Exercise Trojan Footprint' training of medical and casualty night evacuations, during a media tour of the special operations, in Spilve, Latvia, May 10, 2022. REUTERS/Remo Casilli

A self-propelled gun, Panzerhaubitze 2000, is seen during training at a German army base on a NATO media day, in which up to 7,500 soldiers from 9 nations take part, in Munster, Germany, May 10, 2022. REUTERS/Fabian Bimmer