Ukrainian President Volodymyr Zelenskiy has thanked the Polish nation "for all the support given during this difficult time of Russian aggression."
He made the comments during a joint news conference in Warsaw on August 31 with Polish President Andrzej Duda, who said he had assured Zelenskiy that "he can count on me when it comes to the sovereignty, independence, and integrity of Ukraine's territory."
Zelenskiy arrived in Poland on August 31 on a two-day state visit for talks on the policies of Ukraine's newly appointed government, the country's ties with the European Union, and the conflict in eastern Ukraine in which more than 13,000 have died in fighting between Ukrainian government forces and Russia-backed separatists since April 2014.
WATCH: Zelenskiy Thanks Poland For Its Support Against Russian Aggression
On September 1, he will take part in ceremonies in Warsaw marking the 80th anniversary of the start of World War II -- the invasion of Poland by Nazi Germany on September 1, 1939.
Addressing reporters, President Duda said he told Zelenskiy that "Ukraine needs to go back to the territorial integrity it used to have before 2014," when Russia annexed Ukraine's Crimean Peninsula.
In turn, Zelenskiy told Duda that "we value highly the principled stand, the decisiveness, and the high professionalism of your representatives at the UN Security Council, European Union, NATO, and other international organizations."
"We have coordinated the next steps to stop the war in eastern Ukraine," he added.
U.S. national-security adviser John Bolton said on a visit to Kyiv earlier this week that President Donald Trump could meet Zelenskiy in Warsaw this weekend. However, Trump cancelled his plans to attend the World War II ceremony in Warsaw, citing Hurricane Dorian, which is set to make landfall in Florida this weekend.
Bolton’s visit was the first by a senior U.S. official since Zelenskiy's landslide election victory in May. Washington is a key ally for Kyiv, having imposed sanctions on Russia for annexing Crimea in 2014 and backing pro-Moscow separatists in Ukraine’s east.
The members of Zelenskiy's new government, appointed on August 29, are on average just under 40 years old. Oleksiy Honcharuk, 35, became the nation’s youngest prime minister, beating the previous record held by his predecessor, Volodymyr Hroysman.
Zelenskiy, a comedian-turned-politician who has pledged to “break the system” in Ukrainian politics, is Ukraine’s youngest president at 41.