Russia annexed Crimea in 2014, but the region remains internationally recognized as part of Ukraine.
Gitanas Nauseda was in Warsaw addressing a remote session of Poland's and Lithuania's parliaments, marking the 230th anniversary of their joint constitution, Europe's first such written democratic document.
Russia's Defense Ministry tweeted footage of a Black Sea Fleet warship firing a Vulkan missile.
"Does Ukraine want war? No. Is it ready for it? Yes," Zelensky said during a Tuesday address to his nation.
Russia's defense minister on Tuesday declared that the U.S. has employed "provocative actions" in the Black Sea amid escalating tensions with Ukraine.
Facing sanctions on many fronts, the Russian president extended by a year its own measures on countries that have tried to punish Moscow.
While jellyfish are fairly common in the area, such large congregations are quite unusual at this time of year.
The two men met on the sidelines of the United Nations General Assembly amid allegations that Trump asked Zelensky to investigate accusations of corruption against 2020 rival Joe Biden.
The U.S. has been sending military aid to Ukraine to help its forces battle Russian-backed separatists in the east of the country.
Volodymyr Zelensky also thanked the U.S. for its continued support, noting he hoped to visit the White House soon for a meeting with Trump.
The current affairs show 60 Minutes on the Kremlin-backed channel Channel 1 poked fun at the U.S. president's promotion of his Russian counterpart at the G-7 summit which has just finished.
"I've never seen it before," the former GOP congressman said, pointing out that the attack came "in defense of an autocrat."
"Under no condition can we agree with this logic," European Council President Donald Tusk said.
Where I had reason to believe a sensitive example could lead to a book being banned, I authorized replacing it.
The author replaced criticism of Putin with attacks on President Donald Trump and softened his description of Moscow's annexation of Crimea.
Remains belonging to one of the biggest birds that ever lived have been discovered in a cave in Crimea.
One military expert said Crimea is "bristling with missiles like a hedgehog."
"It is too early to talk about President Putin's offering his congratulations to Zelensky, as well as speaking about the possibilities of working together," a Kremlin spokesperson said about comedian-actor Volodymyr Zelensky, Ukraine's new president.
"This is a sure sign of your successful work in Russia," Russian President Vladimir Putin told a director from the country's Ministry of Energy.
The Trump administration recently announced that it would pull out of the INF treaty, which was signed between the U.S. and the Soviet Union in 1987.
Months after Russia seized three Ukrainian navy ships in the Sea of Azov, the project is more relevant than ever.
"We know that we can only solve things through being reasonable and through dialogue," the German chancellor said.
The S-400 system is considered the most advanced in the world.
Ukrainian President Petro Poroshenko said that the number of Russia forces at the border had "grown dramatically."