Russian drones hit a military hospital, shopping centre and apartment blocks in Ukraine's second-largest city, Kharkiv, killing two people and wounding dozens, while U.S. President Donald Trump voiced anger at Russian President Vladimir Putin for comments he made about the leader of Ukraine.

Ukraine's General Staff of the Armed Forces denounced the "deliberate, targeted shelling" of the military hospital late Saturday. Among the casualties were service members who were undergoing treatment, it said. Regional Gov. Oleh Syniehubov said those killed were a 67-year-old man and a 70-year-old woman.

According to Ukrainian government and military analysts, Russian forces are preparing to launch a fresh military offensive in the coming weeks to maximize pressure on Kyiv and strengthen the Kremlin's negotiating position in ceasefire talks.

Ukraine's air force reported that Russia fired 111 exploding drones and decoys in the latest wave of attacks overnight into Sunday. It said 65 of them were intercepted and another 35 were lost, likely having been electronically jammed.

Ukrainian President Volodymyr Zelenskyy said on Sunday that over the past week "most regions of Ukraine" came under Russian attack. In a social media post, he said that "1,310 Russian guided aerial bombs, over 1,000 attack drones — mostly 'Shaheds' — and nine missiles of various types, including ballistic ones" had been launched against Ukraine.

Zelenskyy also repeated his assertion that "Russia is dragging out the war," echoing comments he made Thursday in Paris that Russia is prolonging ceasefire talks "just to buy time and then try to grab more land."

Russia's Ministry of Defence, meanwhile, said its air defence systems shot down six Ukrainian drones. It also claimed on Sunday that its troops had taken control of a village in Ukraine's partly occupied Donetsk region. The Russian claim could not be independently verified, and Ukraine did not comment.

Trump threatens Russia with sanctions

In an early Sunday morning phone interview with NBC News, Trump referred to comments Putin made on Friday about temporarily putting Ukraine under external governance. Trump said he was "angry, pissed off" when Putin "started getting into Zelenskyy's credibility."

Putin repeated his claim that Zelenskyy, whose term expired last year, lacks the legitimacy to sign a peace deal. Under Ukraine's constitution, it is illegal for the country to hold national elections while it's under martial law.

"If a deal isn't made, and if I think it was Russia's fault, I'm going to put secondary sanctions on Russia," Trump told Kristen Welker, adding that there would be "a 25- to 50-point tariff on all oil."

"Anybody buying oil from Russia will not be able to sell their product, any product, not just oil, into the United States," he said.

Nonetheless, Trump reiterated that he and Putin have a "very good relationship."