"Millions" could die in Ukraine's war with Russia if US lawmakers don't approve President Joe Biden's $60 billion ($AUD 91 billion) aid request for Kyiv, Ukrainian President Volodymyr Zelensky told CNN on Sunday.
Asked by CNN's Kaitlan Collins about a claim made by US Senator JD Vance that the outcome of the war would not change even if Ukraine receives the money, Zelensky said he wasn't sure Vance "understands what is going on here".
"To understand it is to come to the front line to see what's going on, to speak with the people, then to go to civilians to understand … what will (happen to) them without this support. And he will understand that millions … will be killed. It's a fact," Zelensky said.
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"Of course he doesn't understand, God bless you don't have the war on your territory," he added.
Zelensky's warning came just hours after the Ukrainian leader made a rare admission of troop losses, saying that about 31,000 Ukrainian soldiers have been killed so far in the conflict, during a conference in Kyiv.
Addressing the conference, Zelensky disputed Russian claims of much higher numbers when it comes to Ukrainian casualties.
He added that "tens of thousands" of civilians have died in Ukrainian territory occupied by Russian forces.
"It's a big loss to us. 31,000 Ukrainians, Ukrainian soldiers, died in this war. Not 300,000. Not 150,000, whatever (Russian President Vladimir) Putin is lying with," Zelensky said.
"Every loss is a huge loss to us."
CNN cannot independently verify the numbers, which come on the weekend Ukraine marked two years since Russia's full-scale invasion.
Throughout the conflict, Kyiv has been hesitant to admit how many soldiers have been killed.
Former Ukraine Defense Minister Oleksiy Reznikov said in June 2022 that he believed tens of thousands of Ukrainians had been killed since February of that year.
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Two months later, Valerii Zaluzhnyi, then the head of Ukraine's armed forces, said 9000 troops had been killed.
US officials estimate some 70,000 soldiers have been killed and nearly twice that number wounded.
Russia, meanwhile, has lost a staggering 87 per cent of the total number of active-duty ground troops it had prior to the invasion, a source familiar with a declassified US intelligence assessment provided to Congress told CNN in December.
Zelensky's comments come as his country faces setbacks on the battlefield and is struggling to secure more aid from its Western partners.
In the United States, a foreign aid bill remains stalled in the House of Representatives by isolationist Republicans.
The Ukrainian leader said his country is counting on Congress to act.
"They know we need their support," said Zelensky.
Zelensky also floated the possibility of attending a possible peace summit in Switzerland in the spring, though cautioned Russia may not be involved.
He said that Putin "does not want to end this war".
