Russia and Ukraine swapped accusations of breaking a U.S.-brokered ceasefire on Sunday, with both sides claiming to have suffered casualties in drone and artillery strikes over the past 24 hours.

Ukraine’s President Volodymyr Zelenskyy said that Russia was neither observing the truce nor “even particularly trying to,” adding there had been no calm in frontline areas despite a lull in large-scale attacks and pledged that Ukraine would retaliate to any aggression shown by Moscow.

“Yesterday and today, Ukraine refrained from long-range retaliatory actions in response to the absence of large-scale Russian attacks,” Zelenskyy said in evening statement, stressing Ukraine’s increasing ability to hit targets far inside Russia.

“We will continue to respond in the same mirrorlike manner, and if the Russians decide to return to full-scale warfare, our response will be immediate and significant,” he said.

Ivan Fedorov, head of Ukraine’s southeastern Zaporizhzhia region, said one person was killed and three others wounded by Russian artillery and drone attacks in the last 24 hours. Another 16 people were also wounded in attacks across other regions of Ukraine, local officials said.

Russia’s defense ministry, meanwhile, accused Kyiv of committing more than 1,000 ceasefire violations, state media reported, citing a daily briefing. The ministry said Ukrainian forces had attacked civilian targets in several Russian regions and carried out strikes against Russian military positions on the front line.

Russia’s military had “responded in kind” to the ceasefire violations, the ministry said.

Two people were injured by Ukrainian shelling in the Russian-occupied part of Ukraine’s Kherson region, the area’s Moscow-installed leader Vladimir Saldo said.

U.S. President Donald Trump said Friday that Russia and Ukraine had bowed to his request for a ceasefire running Saturday through Monday to mark Victory Day, the Russian celebration marking the defeat of Nazi Germany.