“There is no room in the Europe of the 21st century for new areas of influence that negate the sovereignty of independent countries," Nauseda said.
During a later televised debate among the presidents, Poland's Andrzej Duda assured Zelenskyy it was also Warsaw's view that Russia's actions in Ukraine “must not be accepted.”
Zelenskyy, who is to meet with U.S. Secretary of State Antony Blinken this week in Kyiv, said that the war against Moscow-backed separatists in eastern Ukraine means that “there is war in Europe.”
“No one today will give up our sovereignty. We are fighting ... because we want to be free,” Zelenskyy said.
Following one-on-one talks with Duda, Zelenskyy thanked Poland for its strong support for Ukraine's territorial integrity and condemnation of Crimea's annexation.
Zelenskyy said he invited Duda to ceremonies in August marking 30 years of Ukraine's independence and to the accompanying meeting of state leaders that is to discuss the “de-occupation of Crimea."
During the presidents' debate Monday on the European Union and the pandemic, Zelenskyy said that Ukraine, which is aspiring to one day join the club, said it has not yet received any of the promised COVID-19 vaccines from the EU.
He said only 1 million people in his nation of more than 44 million have been immunized.
The five presidents signed a declaration stressing that solidarity among nations is the basis for peace, stability and development in today's world.
Poland’s 1791 Constitution was intended to strengthen its political system and rule of law and protect it against aggression from neighboring powers, including Russia. Historians say the effort came too late, and failed to avert annexations by the Russian, Prussian and Austrian empires that in 1795 wiped Poland from maps for more than a century.
Poland and neighboring Lithuania were one state at the time of the 18th-century constitution.