Russia's latest strike on Odesa on Sunday killed two people and severely damaged a historic Orthodox cathedral, drawing a vow of retaliation from Ukraine's leader.
The attack came as President Vladimir Putin met his Belarusian counterpart for talks in Russia and claimed Kyiv's counteroffensive had "failed".
Russia has pounded the Ukrainian port city of Odesa since quitting the Black Sea grain deal last week.
Locals watched in disbelief as the Transfiguration Cathedral -- originally built in 1794 under imperial Russian rule -- was hit.
The biggest Orthodox church in Odesa lies within the UNESCO-protected historic city centre.
UNESCO condemned the "brazen" attack, which hit several sites in the World Heritage area, marking "an escalation of violence against (the) cultural heritage of Ukraine", according to UNESCO chief Audrey Azoulay.
Clergymen rescued icons from rubble inside the badly damaged shrine, which was demolished under Stalin in 1936 and rebuilt in the 1990s after the collapse of the Soviet Union.
The culture ministry said it had so far identified damage to 29 monuments of important cultural heritage.
The Ukrainian government condemned the cathedral strike as a "war crime", saying it had been "destroyed twice: by Stalin and Putin".
President Volodymyr Zelensky vowed retaliation: "They will definitely feel this," he said.
"We cannot allow people around the world to get used to terrorist attacks," Zelensky added in his evening speech late on Sunday.
"The target of all these missiles is not just cities, villages or people. Their target is humanity and the foundations of our entire European culture."
- Icons pulled from the rubble -
Images showed smashed mosaics on the cathedral floor as workers cleared the rubble. The outside of the building appeared intact.
"There was a direct hit to the cathedral," said Father Myroslav, the assistant rector, adding that three altars were ruined.
Icons were pulled out from under the rubble and the shrine was "very badly damaged inside", with "only the bell tower intact", he added.
Clergymen said a security guard and a priest getting ready for a morning liturgy were inside during the attack but both survived.
Russia blamed the cathedral damage on Ukrainian air defence. It said it had hit all its intended targets in the Odesa strike, claiming the sites were being used to prepare "terrorist acts" against Russia.
But local people said Russia had hit residential areas.
"We have ordinary residential buildings here, where people live," a woman who owns a beauty salon nearby, Tetiana, told AFP.
"There are no military facilities here. Just simple beauty salons, a marine agency, a groomer. Nothing military here at all."
Russia launched a wave of attacks on the Black Sea port this week, after exiting a deal between Moscow, Kyiv, Istanbul and the UN allowing the safe passage of cargo ships.
Ukraine has vowed to find a way to continue exports from the ports and said Sunday repeated Russian strikes on Odesa this week were an attempt to "prevent and neutralise international efforts to restore the functioning of the "grain corridor."
- Putin meets Lukashenko -
As Odesa cleared rubble from the Russian strikes, Putin hosted his closest ally, Belarus leader Alexander Lukashenko, in his native city of Saint Petersburg -- their first meeting since Minsk helped end a revolt by Russia's Wagner force.
Both leaders were dismissive of the Ukrainian counteroffensive to take back land captured by Russia.
"There is no counteroffensive," Lukashenko said at the meeting, before being interrupted by Putin: "There is one, but it has failed."
The Belarus strongman now hosts Wagner fighters on his territory, after brokering a deal that convinced its leader Yevgeny Prigozhin to end a march on Moscow and exile himself to Belarus.
"We are controlling what is happening (with Wagner)," he said, thanking Putin for vowing to defend Belarus should it be attacked.
Wagner's presence in Belarus has rattled EU and NATO member Poland, which has strengthened its border.
On Sunday, Polish Defence Minister Mariusz Blaszczak said a new battalion of sappers would be formed in the country's northeast.
Polish, US, British, Romanian and Croatian soldiers were training "shoulder to shoulder", he said, during a visit to the northeastern city of Augustow.
The comments came two days after Putin said western Poland was a "gift" from Stalin at the end of World War II, when victorious allies decided on the contours of post-war Europe. Warsaw summoned the Russian ambassador over the remarks.
Both Putin and Lukashenko also accused Warsaw of having territorial ambitions on Ukraine and Belarus.
Ukraine's Foreign Minister Dmytro Kuleba responded quickly on Twitter.
"Putin's attempts to drive a wedge between Kyiv and Warsaw are as futile as his failing invasion of Ukraine," he wrote.
"Unlike Russia, Poland and Ukraine have learned from history and will always stand united against Russian imperialism and disrespect for international law."
Fighting in Ukraine continued Sunday, with Russia launching 17 cruise missiles and two ballistic missiles, according to the Ukraine army.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
