Zelensky said it would be “difficult” for Ukraine to “stay” without the aid.
He said, “if Ukraine loses the war, other states will be attacked.”
Russia’s invasion of Ukraine has dragged on for more than two years.
Kyiv said Sunday that a Russian strike on the town of Gulyaipole in the southern Zaporizhzhia region killed three people.
“Two men and a woman died under the rubble of their own private house, which was hit by a Russian shell,” the head of the region, Ivan Fedorov, said on social media.
Officials said another civilian, a woman, was killed in the city of Kupiansk, in the northeastern Kharkiv region that has seen increased attacks in recent months.
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“A woman died under the rubble in an apartment on the fourth floor of a high-rise building,” Ukraine’s state emergency services said, adding that it was a residential building.
Authorities in the main city of Kharkiv said Russia launched another attack on Sunday, wounding five civilians, a day after a deadly attack there.
Russia, meanwhile, said a young woman was killed by a Ukrainian drone strike on the Belgorod border region.
Belgorod governor, Vyacheslav Gladkov said shrapnel hit a car with a family of six inside in the village of Shagarovka, some 35 kilometres (20 miles) from the border with Ukraine.
“Unfortunately, a girl died,” Gladkov said, without specifying whether she was a minor. “She died from her wounds on the spot.”
Gladkov said her father had a head wound and that two children were taken to hospital.
