Russia faced international condemnation after a Sunday strike on Ukraine that claimed the lives of at least 34 people.
World leaders denounced the missile attack – one of the worst in recent months – as U.S. President Donald Trump labeled the attack a “horrible thing” and a “mistake.”
Two ballistic missiles hit the center of the northeastern city of Sumy, close to the Russian border, on Sunday morning, killing 34 and wounding more than 100 others, Ukrainian authorities said.
The strike came two days after U.S. presidential envoy Steve Witkoff traveled to Russia to meet President Vladimir Putin and push Trump's efforts to end the more than three-year war.
"I think it was terrible. And I was told they made a mistake. But I think it's a horrible thing. I think the whole war is a horrible thing," U.S. President Trump told reporters on board Air Force One while headed back to Washington on Sunday evening.
Asked to clarify what he meant by a "mistake," Trump said that "they made a mistake ... you're gonna ask them" – without specifying who or what he was referring to.
U.S. Secretary of State Marco Rubio called the attack "horrifying" and a "tragic reminder of why President Trump and his administration are putting so much time and effort into trying to end this war and achieve durable peace."
Ukraine's President Volodymyr Zelenskyy on Sunday urged Trump to visit his country to understand better the devastation wrought by Russia's invasion.
"Please, before any kind of decisions, any kind of forms of negotiations, come to see people, civilians, warriors, hospitals, churches, children destroyed or dead," he said, according to a transcript of an interview broadcast on CBS.
Zelenskyy stressed that the attack occurred on Palm Sunday, a major Christian feast.
"Only completely deranged scum can do something like this," he said in his Sunday evening address.
U.N. Secretary-General Antonio Guterres was "deeply alarmed and shocked" by the strike, which highlighted a "devastating pattern of similar assaults on Ukrainian cities and towns in recent weeks," his spokesman Stephane Dujarric said.
It was the second Russian attack this month to cause a large civilian death toll. An attack on Zelenskyy's home city of Kryvyi Rih killed at least 18 people, including nine children.
Trump is pushing for a quick end to the war, with the United States holding direct talks with Russia despite its unrelenting attacks on Ukraine.
Washington has also held talks with Ukrainian officials on a potential truce, while European nations are discussing a military deployment to reinforce any Ukraine cease-fire.
Kyiv has previously agreed to a U.S.-proposed unconditional cease-fire but Moscow has turned it down.
Zelenskyy called on the United States and Europe to give a "strong response" to Russia, adding: "Talking has never stopped ballistic missiles and bombs."
Trump has previously voiced anger at Russia for "bombing like crazy" in Ukraine.
France's President Emmanuel Macron said the strike on Sumy showed Russia's "blatant disregard for human lives, international law and the diplomatic efforts of President Trump."
British Prime Minister Keir Starmer said he was "appalled" by the attack, which Italian counterpart Giorgia Meloni described as a "cowardly" act by Russia.
Germany's chancellor-in-waiting Friedrich Merz described it as "a serious war crime, deliberate and intended."
Russia has relentlessly attacked Ukraine in recent weeks.
Sumy has been under increasing pressure since Moscow pushed back many of Ukraine's troops from its Kursk region inside Russia, across the border.
Kyiv has warned for weeks that Moscow could mount an offensive on the city.
Russia launched its invasion partially through the Sumy region and briefly occupied parts of it before being pushed back by Ukrainian forces.
On Sunday, Russia said it captured another village in eastern Ukraine's Donetsk region.
