NATO Secretary General Jens Stoltenberg, left, greets Ukraine's Foreign Minister Dmytro Kuleba with an elbow bump prior to a meeting at NATO headquarters in Brussels, Tuesday, April 13, 2021. (AP Photo/Francisco Seco, Pool)

Ukraine's Foreign Minister Dmytro Kuleba, second left, arrives prior to a meeting with NATO Secretary General Jens Stoltenberg at NATO headquarters in Brussels, Tuesday, April 13, 2021. (AP Photo/Francisco Seco, Pool)

NATO Secretary General Jens Stoltenberg, left, greets Ukraine's Foreign Minister Dmytro Kuleba with an elbow bump prior to a meeting at NATO headquarters in Brussels, Tuesday, April 13, 2021. (AP Photo/Francisco Seco, Pool)

NATO Secretary General Jens Stoltenberg, right, and Ukraine's Foreign Minister Dmytro Kuleba take off their protective face masks prior to an official greeting at NATO headquarters in Brussels, Tuesday, April 13, 2021. (AP Photo/Francisco Seco, Pool)

NATO Secretary General Jens Stoltenberg, right, and Ukraine's Foreign Minister Dmytro Kuleba pose for photographers prior to a meeting at NATO headquarters in Brussels, Tuesday, April 13, 2021. (AP Photo/Francisco Seco, Pool)

NATO Secretary General Jens Stoltenberg, right, speaks with Ukraine's Foreign Minister Dmytro Kuleba prior to a meeting at NATO headquarters in Brussels, Tuesday, April 13, 2021. (AP Photo/Francisco Seco, Pool)

NATO Secretary General Jens Stoltenberg, right, and Ukraine's Foreign Minister Dmytro Kuleba participate in a media conference at NATO headquarters in Brussels, Tuesday, April 13, 2021. NATO Secretary General Jens Stoltenberg and Ukrainian Foreign Minister Dmytro Kuleba met Tuesday to discuss Russia's troop buildup troops along the frontier with Ukraine. (AP Photo/Francisco Seco, Pool)

NATO Secretary General Jens Stoltenberg speaks during a media conference at NATO headquarters in Brussels, Tuesday, April 13, 2021. NATO Secretary General Jens Stoltenberg and Ukrainian Foreign Minister Dmytro Kuleba met Tuesday to discuss Russia's troop buildup troops along the frontier with Ukraine. (AP Photo/Francisco Seco, Pool)

Ukraine's Foreign Minister Dmytro Kuleba speaks during a media conference at NATO headquarters in Brussels, Tuesday, April 13, 2021. NATO Secretary General Jens Stoltenberg and Ukrainian Foreign Minister Dmytro Kuleba met Tuesday to discuss Russia's troop buildup troops along the frontier with Ukraine. (AP Photo/Francisco Seco, Pool)

NATO Secretary General Jens Stoltenberg, right, and Ukraine's Foreign Minister Dmytro Kuleba put on their protective face masks after addressing a media conference at NATO headquarters in Brussels, Tuesday, April 13, 2021. NATO Secretary General Jens Stoltenberg and Ukrainian Foreign Minister Dmytro Kuleba met Tuesday to discuss Russia's troop buildup troops along the frontier with Ukraine. (AP Photo/Francisco Seco, Pool)

NATO Secretary General Jens Stoltenberg, right, and Ukraine's Foreign Minister Dmytro Kuleba participate in a media conference at NATO headquarters in Brussels, Tuesday, April 13, 2021. NATO Secretary General Jens Stoltenberg and Ukrainian Foreign Minister Dmytro Kuleba met Tuesday to discuss Russia's troop buildup along the frontier with Ukraine. (AP Photo/Francisco Seco, Pool)

NATO Secretary General Jens Stoltenberg speaks during a media conference at NATO headquarters in Brussels, Tuesday, April 13, 2021. NATO Secretary General Jens Stoltenberg and Ukrainian Foreign Minister Dmytro Kuleba met Tuesday to discuss Russia's troop buildup along the frontier with Ukraine. (AP Photo/Francisco Seco, Pool)

Ukraine's Foreign Minister Dmytro Kuleba participate in a media conference at NATO headquarters in Brussels, Tuesday, April 13, 2021. NATO Secretary General Jens Stoltenberg and Ukrainian Foreign Minister Dmytro Kuleba met Tuesday to discuss Russia's troop buildup along the frontier with Ukraine. (AP Photo/Francisco Seco, Pool)

United States Secretary of State Antony Blinken, right, waits for the start of a meeting with Ukrainian Foreign Minister Dmytro Kuleba in Brussels, Tuesday, April 13, 2021. (Johanna Geron, Pool via AP)

Ukrainian Foreign Minister Dmytro Kuleba, left, meets with United States Secretary of State Antony Blinken, right, in Brussels, Tuesday, April 13, 2021. (Johanna Geron, Pool via AP)

Ukrainian Foreign Minister Dmytro Kuleba, left, waits for the start of a meeting to take place with United States Secretary of State Antony Blinken in Brussels, Tuesday, April 13, 2021. (Johanna Geron, Pool via AP)

NATO Secretary General Jens Stoltenberg (L) greets Ukraine's Foreign Minister Dmytro Kuleba with an elbow bump prior to a meeting at NATO headquarters in Brussels, on April 13, 2021. (Photo by Francisco Seco / POOL / AFP)

NATO Secretary General Jens Stoltenberg (L) greets Ukraine's Foreign Minister Dmytro Kuleba with an elbow bump prior to a meeting at NATO headquarters in Brussels, on April 13, 2021. (Photo by Francisco Seco / POOL / AFP)

NATO Secretary General Jens Stoltenberg (R) welcomes Ukraine's Foreign Minister Dmytro Kuleba prior to a meeting at NATO headquarters in Brussels, on April 13, 2021. (Photo by Francisco Seco / POOL / AFP)

Ukraine's Foreign Minister Dmytro Kuleba (2ndL) arrives for a meeting with NATO Secretary general at NATO headquarters in Brussels, on April 13, 2021. (Photo by Francisco Seco / POOL / AFP)

NATO Secretary General Jens Stoltenberg (R) welcomes Ukraine's Foreign Minister Dmytro Kuleba take off their protective face masks prior to an official greeting at NATO headquarters in Brussels, on April 13, 2021. (Photo by Francisco Seco / POOL / AFP)

NATO Secretary General Jens Stoltenberg (R) welcomes Ukraine's Foreign Minister Dmytro Kuleba pose prior to their meeting at NATO headquarters in Brussels, on April 13, 2021. (Photo by Francisco Seco / POOL / AFP)

NATO Secretary General Jens Stoltenberg (R) and Ukraine's Foreign Minister Dmytro Kuleba give a press conference following their meeting at NATO headquarters in Brussels, on April 13, 2021. (Photo by Francisco Seco / POOL / AFP)

Ukraine's Foreign Minister Dmytro Kuleba gives a press conference following his0 meeting with NATO Secretary general at NATO headquarters in Brussels, on April 13, 2021. (Photo by Francisco Seco / POOL / AFP)

NATO Secretary General Jens Stoltenberg (R) and Ukraine's Foreign Minister Dmytro Kuleba put on their protective face masks after giving a press conference following their meeting at NATO headquarters in Brussels, on April 13, 2021. (Photo by Francisco Seco / POOL / AFP)

NATO Secretary General Jens Stoltenberg gives a press conference following his meeting with Ukraine's Foreign minister at NATO Secretary general at NATO headquarters in Brussels, on April 13, 2021. (Photo by Francisco Seco / POOL / AFP)

NATO Secretary General Jens Stoltenberg (R) and Ukraine's Foreign Minister Dmytro Kuleba give a press conference following their meeting at NATO headquarters in Brussels, on April 13, 2021. (Photo by Francisco Seco / POOL / AFP)

Ukraine's Foreign Minister Dmytro Kuleba gives a press conference following his0 meeting with NATO Secretary general at NATO headquarters in Brussels, on April 13, 2021. (Photo by Francisco Seco / POOL / AFP)

US Secretary of State Antony Blinken meets with Ukrainian Foreign Minister in Brussels on April 13, 2021. (Photo by JOHANNA GERON / POOL / AFP)

US Secretary of State Antony Blinken (R) meets with Ukrainian Foreign Minister Dmytro Kuleba (L) in Brussels on April 13, 2021. (Photo by JOHANNA GERON / POOL / AFP)

Ukrainian Foreign Minister Dmytro Kuleba (L) meets with US Secretary of State in Brussels on April 13, 2021. (Photo by JOHANNA GERON / POOL / AFP)

BRUSSELS, BELGIUM - APRIL 13: Minister of Foreign Affairs of Ukraine Dmytro Kuleba (L) and Secretary General of NATO Jens Stoltenberg (R) hold a joint press conference in Brussels, Belgium on April 13, 2021. NATO/Pool / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - APRIL 13: Minister of Foreign Affairs of Ukraine Dmytro Kuleba (L) and Secretary General of NATO Jens Stoltenberg (R) hold a joint press conference in Brussels, Belgium on April 13, 2021. NATO/Pool / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - APRIL 13: Minister of Foreign Affairs of Ukraine Dmytro Kuleba (L) and Secretary General of NATO Jens Stoltenberg (R) hold a joint press conference in Brussels, Belgium on April 13, 2021. NATO/Pool / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - APRIL 13: Minister of Foreign Affairs of Ukraine Dmytro Kuleba (2nd L) meets Secretary General of NATO Jens Stoltenberg (C) in Brussels, Belgium on April 13, 2021. NATO/Pool / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - APRIL 13: Minister of Foreign Affairs of Ukraine Dmytro Kuleba and Secretary General of NATO Jens Stoltenberg (not seen) hold a joint press conference in Brussels, Belgium on April 13, 2021. NATO/Pool / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - APRIL 13: Minister of Foreign Affairs of Ukraine Dmytro Kuleba (L) meets Secretary General of NATO Jens Stoltenberg (R) in Brussels, Belgium on April 13, 2021. NATO/Pool / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - APRIL 13: Minister of Foreign Affairs of Ukraine Dmytro Kuleba (R) meets Secretary General of NATO Jens Stoltenberg (L) in Brussels, Belgium on April 13, 2021. NATO/Pool / Anadolu Agency/ABACAPRESS.COM