Volodymyr Zelenskyy has urged US President Donald Trump to visit Ukraine after a Russian missile attack on the north-eastern city of Sumy left 34 dead, including two children.
Warning: Graphic images
Moscow claimed two of its missiles hit a meeting of Ukrainian military officers in the attack, on Palm Sunday, which left 119 people injured and was the deadliest strike by Russian forces this year.
It comes as the new Trump administration has been attempting to broker a peace deal that will bring an end to the three-year conflict.
The Ukrainian president used an interview with the US broadcasters CBS to call on Mr Trump to visit his country to see the devastation for himself.
"Please come to see people, civilians, warriors, hospitals, churches, children, destroyed or dead," he said in a video clip the program posted on social media.
During the interview, Mr Zelenskyy was asked if the United States had Ukraine's back.
"Even in this pause of mine, there's a problem, because I want to answer truthfully and quickly that the United States is our strategic, strong partner," the president replied after a brief pause.
"But the pause is doubt. I don't doubt that the people of America are with us, but in a long war, many details are forgotten."
The US president did not acknowledge his Ukrainian counterpart's invitation when he posted on Truth Social about the conflict on Monday, local time.
Calling the conflict "Biden’s war, not mine", he repeated the inaccurate claim that Kviv bore responsibility for Russia's invasion.
He said: "President Zelenskyy and Crooked Joe Biden did an absolutely horrible job in allowing this travesty to begin. There were so many ways of preventing it from ever starting. But that is the past. Now we have to get it to STOP, AND FAST."
Mr Zelenskyy said separate strikes on the southern city of Odessa injured another seven people, in a Russian barrage that also targeted the cities of Sloviansk, Uman, Kharkiv and Berislav.
"Russian terror continues every day and every night," he said.
"Only real pressure on Russia can stop this. We need tangible sanctions against those sectors that finance the Russian killing machine.
"The one who brought the war must stop and answer for what he has done — that is only fair."
He also called on the US to provide forces as part of an international peacekeeping effort, specifically asking for Washington to help protect Ukrainian airspace with aircraft.
The comments came before Russia's defence ministry said that its forces had fired "two Iskander-M tactical missiles at the meeting venue" of what it called an operational tactical group of Ukraine's armed forces in Sumy on Sunday.
The Kremlin accused Kyiv of using civilians as "human shields".
Russia claimed that more than 60 Ukrainian soldiers were killed in the strike, and its defence ministry also accused Ukraine of using civilians as human shields by placing military facilities and holding events involving soldiers in the centre of a densely populated city.
There was no immediate response from Kyiv to the "human shield" accusation.
The strike in Sumy was one of the deadliest attacks on Ukraine by Russia in months, and the leaders of Britain, Germany and Italy condemned the attack in Sumy on Sunday.
Sumy, with a population of around a quarter of a million and located just over 25 kilometres from the Russian border, became a garrison city when Kyiv's forces launched an incursion into Russia in August.
Sumy's acting mayor, Artem Kobzar, announced three days of mourning for the victims starting from Monday.
The people who were caught in Sunday's strike were out on the street or inside cars, public transport and buildings when the missiles hit, Interior Minister Ihor Klymenko said.
"Deliberate destruction of civilians on an important church feast day," he wrote.
Andriy Yermak, Zelenskiy's chief of staff, said the missiles contained cluster munitions. "The Russians are doing this to kill as many civilians as possible," he said.
Several European figures have condemned Vladimir Putin over the strike.
Chancellor-in-waiting Friedrich Merz told broadcaster ARD the attack on Sumy was "clearly a war crime ... There is no greater example of perfidy: a targeted and planned war crime".
When asked directly about the attack at the weekend, Mr Trump said that it was terrible.
"And I was told they made a mistake," the US president said without elaborating further.
"But I think it's a horrible thing."
Russian presidential spokesperson Dmitry Peskov was asked at his daily briefing how the Kremlin viewed Mr Trump's comment and whether the strike had been conducted in error.
He replied that the Kremlin did not comment on the course of the war, and this was a matter for the defence ministry.
"I can only repeat and remind you of the repeated statements of both our president and our military representatives that our military strikes exclusively at military and military-adjacent targets," he said.
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