Ukrainian President Volodymyr Zelensky said Sunday that Russia could attempt a new offensive as early as late May or early summer.

"They will prepare, and we will prepare for their fight," he said Sunday at a news conference in Kyiv.

His comments come as the president reiterates his nation's need for more weaponry to continue the fight against Russia.

Half of all military aid pledged to Ukraine arrives late, the country's defense minister said at a conference in Kyiv on Sunday, as concern grows about Ukraine's dwindling stockpiles of ammunition.

Zelensky added that the coming months would be difficult for his country because there's political uncertainty in the US.

“The US elections will be a turning point,” he said.

The Ukrainian leader said earlier Sunday that the country is enduring its “most difficult moment,” but that he still has faith at home and abroad.

"If we all fall apart — externally with our partners and, God forbid, internally — then this will be the weakest moment. So far, this has not happened,” Zelensky said.