European Council President Donald Tusk, right, shakes hands with Ukrainian President Petro Poroshenko before their meeting at the European Council headquarters in Brussels, May 13, 2019. (AP Photo/Francisco Seco, Pool)

European Council President Donald Tusk, right, shakes hands with Ukrainian President Petro Poroshenko before their meeting at the European Council headquarters in Brussels, May 13, 2019. (AP Photo/Francisco Seco, Pool)

APTOPIX European Council President Donald Tusk, right, is awarded with Ukrainian Order of Prince Yaroslav the Wise by Ukrainian President Petro Poroshenko before their meeting at the European Council headquarters in Brussels, May 13, 2019. (AP Photo/Francisco Seco, Pool)

European Council President Donald Tusk, right, shakes hands with Ukrainian President Petro Poroshenko after being awarded with Ukrainian Order of Prince Yaroslav the Wise before their meeting at the European Council headquarters in Brussels, May 13, 2019. (AP Photo/Francisco Seco, Pool)

Ukrainian President Petro Poroshenko, left, talks to European Council President Donald Tusk, right, during their meeting at the European Council headquarters in Brussels, May 13, 2019. (AP Photo/Francisco Seco, Pool)

European Council President Donald Tusk, right, is awarded with Ukrainian Order of Prince Yaroslav the Wise by Ukrainian President Petro Poroshenko before their meeting at the European Council headquarters in Brussels, May 13, 2019. (AP Photo/Francisco Seco, Pool)

European Council President Donald Tusk (R) shakes hands with Ukrainian President Petro Poroshenko (L) ahead of their meeting at the European Council headquarters in Brussels, on May 13, 2019. (Photo by Francisco Seco / POOL / AFP)

European Council President Donald Tusk (R) shakes hands with Ukrainian President Petro Poroshenko (L) ahead of their meeting at the European Council headquarters in Brussels, on May 13, 2019. (Photo by Francisco Seco / POOL / AFP)

European Council President Donald Tusk (R) shakes hands with Ukrainian President Petro Poroshenko (L) ahead of their meeting at the European Council headquarters in Brussels, on May 13, 2019. (Photo by Francisco Seco / POOL / AFP)

European Council President Donald Tusk (R) shakes hands with Ukrainian President Petro Poroshenko (L) ahead of their meeting at the European Council headquarters in Brussels, on May 13, 2019. (Photo by Francisco Seco / POOL / AFP)

European Council President Donald Tusk (R) shakes hands with Ukrainian President Petro Poroshenko (L) ahead of their meeting at the European Council headquarters in Brussels, on May 13, 2019. (Photo by Francisco Seco / POOL / AFP)

European Council President Donald Tusk (R) poses as he is awarded with the Ukrainian Order of Prince Yaroslav the Wise by Ukrainian President Petro Poroshenko (L) ahead of their meeting at the European Council headquarters in Brussels, on May 13, 2019. (Photo by Francisco Seco / POOL / AFP)

European Council President Donald Tusk (R) poses as he is awarded with the Ukrainian Order of Prince Yaroslav the Wise by Ukrainian President Petro Poroshenko (L) ahead of their meeting at the European Council headquarters in Brussels, on May 13, 2019. (Photo by Francisco Seco / POOL / AFP)

European Council President Donald Tusk (R) is awarded with the Ukrainian Order of Prince Yaroslav the Wise by Ukrainian President Petro Poroshenko (L) ahead of their meeting at the European Council headquarters in Brussels, on May 13, 2019. (Photo by Francisco Seco / POOL / AFP)

European Council President Donald Tusk (R) speaks with Ukrainian President Petro Poroshenko (L) during their meeting at the European Council headquarters in Brussels, on May 13, 2019. (Photo by Francisco Seco / POOL / AFP)

European Council President Donald Tusk (R) shakes hands with Ukrainian President Petro Poroshenko (L) ahead of their meeting at the European Council headquarters in Brussels, on May 13, 2019. (Photo by Francisco Seco / POOL / AFP)

BRUSSELS, BELGIUM - MAY 13 : European Council President Donald Tusk (R) is awarded with the Ukrainian Order of Prince Yaroslav the Wise by Ukrainian President Petro Poroshenko (L) ahead of their meeting at the European Council headquarters in Brussels, Belgium on May 13, 2019. Dursun Aydemir / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - MAY 13 : European Council President Donald Tusk (R) shakes hands with Ukrainian President Petro Poroshenko (L) ahead of their meeting at the European Council headquarters in Brussels, Belgium on May 13, 2019. Dursun Aydemir / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - MAY 13 : European Council President Donald Tusk (C-L) and Ukrainian President Petro Poroshenko (C) hold a meeting at the European Council headquarters in Brussels, Belgium on May 13, 2019. Dursun Aydemir / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - MAY 13 : European Council President Donald Tusk (R) is awarded with the Ukrainian Order of Prince Yaroslav the Wise by Ukrainian President Petro Poroshenko (L) ahead of their meeting at the European Council headquarters in Brussels, Belgium on May 13, 2019. Dursun Aydemir / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - MAY 13 : European Council President Donald Tusk (R) poses as he is awarded with the Ukrainian Order of Prince Yaroslav the Wise by Ukrainian President Petro Poroshenko (L) ahead of their meeting at the European Council headquarters in Brussels, Belgium on May 13, 2019. Dursun Aydemir / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - MAY 13 : European Council President Donald Tusk (R) and Ukrainian President Petro Poroshenko (L) hold a meeting at the European Council headquarters in Brussels, Belgium on May 13, 2019. Dursun Aydemir / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - MAY 13 : European Council President Donald Tusk (R) and Ukrainian President Petro Poroshenko (L) hold a meeting at the European Council headquarters in Brussels, Belgium on May 13, 2019. Dursun Aydemir / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - MAY 13 : European Council President Donald Tusk (R) is awarded with the Ukrainian Order of Prince Yaroslav the Wise by Ukrainian President Petro Poroshenko (L) ahead of their meeting at the European Council headquarters in Brussels, Belgium on May 13, 2019. Dursun Aydemir / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - MAY 13 : European Council President Donald Tusk (R) shakes hands with Ukrainian President Petro Poroshenko (L) ahead of their meeting at the European Council headquarters in Brussels, Belgium on May 13, 2019. Dursun Aydemir / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - MAY 13 : High Representative of the European Union for Foreign Affairs and Security Policy Federica Mogherini (L), European Council President Donald Tusk (C), Azerbaijani President Ilham Aliyev (L3), President of the European Commission Jean-Claude Juncker (R2), President of Ukraine Petro Poroshenko (R3) and President of Romania Klaus Werner Lohannis (L2) attend the EU Eastern Partnership meeting in Brussels, Belgium on May 13, 2019. Dursun Aydemir / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - MAY 13 : High Representative of the European Union for Foreign Affairs and Security Policy Federica Mogherini (L2), President of Ukraine Petro Poroshenko (L) and President of Romania Klaus Werner Lohannis (R) attend the EU Eastern Partnership meeting in Brussels, Belgium on May 13, 2019. Dursun Aydemir / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - MAY 13 : European Council President Donald Tusk (L), President of Ukraine Petro Poroshenko (C) and President of the European Commission Jean-Claude Juncker (R) attend the EU Eastern Partnership meeting in Brussels, Belgium on May 13, 2019. Dursun Aydemir / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - MAY 13 : European Council President Donald Tusk (R), President of Ukraine Petro Poroshenko (L) and President of Romania Klaus Werner Lohannis (L2) attend the EU Eastern Partnership meeting in Brussels, Belgium on May 13, 2019. Dursun Aydemir / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - MAY 13 : President of the European Commission Jean-Claude Juncker (C), President of Ukraine Petro Poroshenko (L) attend the EU Eastern Partnership meeting in Brussels, Belgium on May 13, 2019. Dursun Aydemir / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - MAY 13 : President of the European Commission Jean-Claude Juncker (R) and President of Ukraine Petro Poroshenko (L) attend the EU Eastern Partnership meeting in Brussels, Belgium on May 13, 2019. Dursun Aydemir / Anadolu Agency/ABACAPRESS.COM

BRUSSELS, BELGIUM - MAY 13 : High Representative of the European Union for Foreign Affairs and Security Policy Federica Mogherini (L), European Council President Donald Tusk (C), Azerbaijani President Ilham Aliyev (L3), President of the European Commission Jean-Claude Juncker (R2), President of Ukraine Petro Poroshenko (R3) and President of Romania Klaus Werner Lohannis (L2) attend the EU Eastern Partnership meeting in Brussels, Belgium on May 13, 2019. Dursun Aydemir / Anadolu Agency/ABACAPRESS.COM